If you're experiencing jQuery issues after a WordPress update, it's likely due to a conflict with outdated or incompatible scripts or plugins. Here's what you can do to troubleshoot and fix the problem:

1. Check for JavaScript Errors:

   Open your browser's developer console (usually by pressing F12 or right-clicking and selecting "Inspect" > "Console" tab) and look for any JavaScript errors. These can provide clues about what's causing the issue.

2. Update Themes and Plugins:

   Make sure all your themes and plugins are up to date. Developers often release updates to ensure compatibility with the latest version of WordPress.

3. Check for Plugin Conflicts:

   Deactivate all plugins and see if the jQuery issue persists. If it's resolved, reactivate each plugin one by one to identify which one is causing the conflict.

4. Check for Theme Conflicts:

   Temporarily switch to a default WordPress theme like Twenty Twenty-One. If the issue is resolved, it indicates a problem with your theme.

5. Use jQuery in NoConflict Mode:

   WordPress runs jQuery in "noConflict" mode to prevent conflicts with other JavaScript libraries. Make sure any custom code or scripts you're using are compatible with this mode.

   Instead of using $ to call jQuery, use jQuery:

   javascript

5. jQuery(document).ready(function($) { // Your code here });

6. Update Custom Code:

   If you have custom JavaScript/jQuery code on your site, ensure it's compatible with the latest version of jQuery. Check for any deprecated functions or methods that might have changed.

7. Check for Deprecated Functions:

   WordPress sometimes deprecates functions and replaces them with newer equivalents. Check if any deprecated jQuery functions are being used and update them.

8. Enqueue jQuery Properly:

   Make sure jQuery is properly enqueued in your theme or plugin. Don't load it from external sources unless absolutely necessary.

9. Disable Minification and Concatenation:

   If you're using a caching or optimization plugin that minifies and concatenates scripts, try disabling this feature to see if it resolves the issue.

10. Clear Browser Cache:

    After making changes, clear your browser's cache to ensure you're not loading outdated scripts.

11. Check for jQuery Migrate:

    If you're using an older theme or plugin, it might rely on jquery-migrate. You can install the "Enable jQuery Migrate Helper" plugin to temporarily restore the jquery-migrate script.

12. Check Plugin Documentation/Support:

    Consult the documentation or support forums of any plugins/themes you suspect might be causing the issue. The developers may have released specific updates or instructions for compatibility.

Remember to always backup your site before making significant changes, especially if you're modifying core files or custom code. This way, you can easily revert to a working state if something goes wrong.