diff --git a/api/strategies/validators.js b/api/strategies/validators.js
index 4cd43e5fc..e8ae300f0 100644
--- a/api/strategies/validators.js
+++ b/api/strategies/validators.js
@@ -1,6 +1,20 @@
 const { z } = require('zod');
 
-const allowedCharactersRegex = /^[a-zA-Z0-9_.@#$%&*()\p{Script=Latin}\p{Script=Common}]+$/u;
+const allowedCharactersRegex = new RegExp(
+  '^[' +
+    'a-zA-Z0-9_.@#$%&*()' + // Basic Latin characters and symbols
+    '\\p{Script=Latin}' + // Latin script characters
+    '\\p{Script=Common}' + // Characters common across scripts
+    '\\p{Script=Cyrillic}' + // Cyrillic script for Russian, etc.
+    '\\p{Script=Devanagari}' + // Devanagari script for Hindi, etc.
+    '\\p{Script=Han}' + // Han script for Chinese characters, etc.
+    '\\p{Script=Arabic}' + // Arabic script
+    '\\p{Script=Hiragana}' + // Hiragana script for Japanese
+    '\\p{Script=Katakana}' + // Katakana script for Japanese
+    '\\p{Script=Hangul}' + // Hangul script for Korean
+    ']+$', // End of string
+  'u', // Use Unicode mode
+);
 const injectionPatternsRegex = /('|--|\$ne|\$gt|\$lt|\$or|\{|\}|\*|;|<|>|\/|=)/i;
 
 const usernameSchema = z
diff --git a/api/strategies/validators.spec.js b/api/strategies/validators.spec.js
index 7f4e02b60..312f06923 100644
--- a/api/strategies/validators.spec.js
+++ b/api/strategies/validators.spec.js
@@ -404,9 +404,6 @@ describe('Zod Schemas', () => {
 
     it('should reject invalid usernames', () => {
       const invalidUsernames = [
-        'Дмитрий', // Cyrillic characters
-        'محمد', // Arabic characters
-        '张伟', // Chinese characters
         'john{doe}', // Contains `{` and `}`
         'j', // Only one character
         'a'.repeat(81), // More than 80 characters