diff --git a/src/Integrations/Divi/Compose/VariableRef.php b/src/Integrations/Divi/Compose/VariableRef.php
index abcbbe4..4de4702 100644
--- a/src/Integrations/Divi/Compose/VariableRef.php
+++ b/src/Integrations/Divi/Compose/VariableRef.php
@@ -35,9 +35,10 @@ use stdClass;
  * DynamicContentOptions::get_options($post_id, 'edit') – option name => its "fields" (key =>
  * field "type"). Always, whatever the map says: "enable_html" is rejected, loop_* names only
  * when the map names them, custom_meta_<key> names and the values of settings whose key ends in
- * "meta_key" (meta_key, select_meta_key, loop_meta_key …) obey META_KEY (ruling S29), and no
- * string – before or after cleaning (ruling S28) – may contain a reference or ")$". A map
- * of another shape fails in the constructor with InvalidArgumentException.
+ * "meta_key" (meta_key, select_meta_key, loop_meta_key …) obey META_KEY after Divi's own prefix
+ * stripping (rulings S29, S30), and no string – before or after cleaning (ruling S28) – may
+ * contain a reference or ")$". A map of another shape fails in the constructor with
+ * InvalidArgumentException.
  */
 final class VariableRef
 {
@@ -80,12 +81,23 @@ final class VariableRef
 
     private const META_PREFIX = 'custom_meta_';
 
+    /**
+     * Prefixes Divi strips from a meta key option with str_replace – every occurrence, not just
+     * the leading one (DynamicContentOptionPostMetaKey.php:232,249,275,286;
+     * DynamicContentOptionLoopPostMetaKey.php:366-373). Ruling S30.
+     */
+    private const META_KEY_PREFIXES = [
+        self::META_PREFIX,
+        'loop_post_meta_key_',
+        'loop_user_meta_key_',
+        'loop_term_meta_key_',
+    ];
+
     private const NUMBER = '/^-?\d+(\.\d+)?$/';
 
     /** @var array<string, array<string, string>> */
     private array $dynamicContent;
 
-    /** @param array<string, array<string, string>>|null $dynamicContent See the class docblock. */
     /**
      * @param array<array-key, mixed>|null $dynamicContent See the class docblock.
      * @throws InvalidArgumentException When the map does not have that shape.
@@ -342,11 +354,26 @@ final class VariableRef
         return $clean;
     }
 
-    /** "telefon", "custom_meta_telefon" yes; "_edit_lock", "custom_meta__edit_lock", "a b" no. */
+    /**
+     * Checks the meta key Divi derives from $key (ruling S30): a leading known prefix is removed the
+     * way Divi does it – str_replace of every occurrence – and a prefix still present afterwards is
+     * rejected (defensive). "telefon", "custom_meta_telefon", "loop_post_meta_key_telefon" yes;
+     * "_edit_lock", "custom_meta__edit_lock", "custom_meta_custom_meta__edit_lock",
+     * "loop_post_meta_key__edit_lock", "a b" no.
+     */
     private static function isMetaKey(string $key): bool
     {
-        if (str_starts_with($key, self::META_PREFIX)) {
-            $key = substr($key, strlen(self::META_PREFIX));
+        foreach (self::META_KEY_PREFIXES as $prefix) {
+            if (str_starts_with($key, $prefix)) {
+                $key = str_replace($prefix, '', $key);
+                break;
+            }
+        }
+
+        foreach (self::META_KEY_PREFIXES as $prefix) {
+            if (str_contains($key, $prefix)) {
+                return false;
+            }
         }
 
         return preg_match(self::META_KEY, $key) === 1;
diff --git a/tests/Unit/Integrations/Divi/Compose/VariableRefTest.php b/tests/Unit/Integrations/Divi/Compose/VariableRefTest.php
index 3b0177e..bfedaf0 100644
--- a/tests/Unit/Integrations/Divi/Compose/VariableRefTest.php
+++ b/tests/Unit/Integrations/Divi/Compose/VariableRefTest.php
@@ -144,6 +144,10 @@ final class VariableRefTest extends TestCase
                 'opacity',
             ],
             'protected meta key' => [self::content('custom_meta__edit_lock', '{}'), 'custom_meta__edit_lock'],
+            'doubled meta prefix' => [
+                self::content('custom_meta_custom_meta__edit_lock', '{}'),
+                'custom_meta_custom_meta__edit_lock',
+            ],
             'loop content outside a loop' => [self::content('loop_post_title', '{}'), 'loop_post_title'],
             'unknown dynamic content' => [self::content('post_meta_key', '{}'), 'post_meta_key'],
             'extra top-level key' => ['$variable({"type":"color","value":{"name":"gcid-a1b2","settings":{}},"x":1})$', 'x'],
@@ -296,6 +300,77 @@ final class VariableRefTest extends TestCase
         }
     }
 
+    /** @return array<string, array{string}> */
+    public static function derivedMetaKeyBypasses(): array
+    {
+        return [
+            'doubled prefix in the name' => [self::content('custom_meta_custom_meta__edit_lock', '{}')],
+            'tripled prefix in the name' => [self::content('custom_meta_custom_meta_custom_meta__edit_lock', '{}')],
+            'prefix rebuilt by the strip' => [self::content('custom_meta_custom_mcustom_meta_eta_telefon', '{}')],
+            'loop prefix in the name' => [self::content('custom_meta_loop_post_meta_key__edit_lock', '{}')],
+            'doubled prefix in select_meta_key' => [
+                self::content('post_meta_key', '{"select_meta_key":"custom_meta_custom_meta__wp_page_template"}'),
+            ],
+            'doubled prefix in meta_key' => [self::content('post_meta_key', '{"meta_key":"custom_meta_custom_meta__x"}')],
+            'loop post prefix' => [self::content('loop_post_meta_key', '{"select_loop_meta_key":"loop_post_meta_key__edit_lock"}')],
+            'loop user prefix' => [self::content('loop_post_meta_key', '{"select_loop_meta_key":"loop_user_meta_key__session_tokens"}')],
+            'loop term prefix' => [self::content('loop_post_meta_key', '{"select_loop_meta_key":"loop_term_meta_key__secret"}')],
+            'doubled loop prefix' => [
+                self::content('loop_post_meta_key', '{"select_loop_meta_key":"loop_post_meta_key_loop_post_meta_key__edit_lock"}'),
+            ],
+            'mixed loop and meta prefix' => [
+                self::content('loop_post_meta_key', '{"select_loop_meta_key":"loop_post_meta_key_custom_meta__edit_lock"}'),
+            ],
+            'mixed meta and loop prefix' => [
+                self::content('post_meta_key', '{"select_meta_key":"custom_meta_loop_term_meta_key__secret"}'),
+            ],
+            'two loop prefixes' => [
+                self::content('loop_post_meta_key', '{"select_loop_meta_key":"loop_user_meta_key_loop_post_meta_key_telefon"}'),
+            ],
+        ];
+    }
+
+    /**
+     * Ruling S30: Divi derives the meta key with str_replace of every prefix occurrence
+     * (DynamicContentOptionPostMetaKey.php:232,275; DynamicContentOptionLoopPostMetaKey.php:366-373).
+     *
+     * @dataProvider derivedMetaKeyBypasses
+     */
+    public function testMetaKeysAreCheckedAfterDivisDerivation(string $value): void
+    {
+        $ref = self::ref([
+            'post_meta_key' => ['meta_key' => 'text', 'select_meta_key' => 'select'],
+            'loop_post_meta_key' => ['select_loop_meta_key' => 'select', 'loop_meta_key' => 'text'],
+        ]);
+
+        $this->expectException(InvalidArgumentException::class);
+
+        $ref->canonical($value, ComposeFixture::sanitizer());
+    }
+
+    public function testDerivedMetaKeysThatAreFineStayAccepted(): void
+    {
+        $ref = self::ref([
+            'post_meta_key' => ['meta_key' => 'text', 'select_meta_key' => 'select'],
+            'loop_post_meta_key' => ['select_loop_meta_key' => 'select', 'loop_meta_key' => 'text'],
+        ]);
+        $sanitizer = ComposeFixture::sanitizer();
+
+        foreach ([
+            self::content('custom_meta_telefon', '{}'),
+            self::content('post_meta_key', '{"select_meta_key":"custom_meta_fax"}'),
+            self::content('loop_post_meta_key', '{"select_loop_meta_key":"loop_post_meta_key_telefon"}'),
+            self::content('loop_post_meta_key', '{"select_loop_meta_key":"loop_user_meta_key_first_name"}'),
+            self::content('loop_post_meta_key', '{"select_loop_meta_key":"loop_term_meta_key_farbe"}'),
+            self::content(
+                'loop_post_meta_key',
+                '{"select_loop_meta_key":"loop_post_meta_key_manual_custom_field_value","loop_meta_key":"telefon"}'
+            ),
+        ] as $value) {
+            self::assertSame($value, $ref->canonical($value, $sanitizer));
+        }
+    }
+
     /** @return array<string, array{array<array-key, mixed>}> */
     public static function malformedMaps(): array
     {