1. Take a backup of your site before updating any extension. You can use Akeeba Backup to take a backup in ZIP format.
2. Check if the website works on your local PC.
3. Install a fresh Joomla and check if there are any issues.
4. If you previously worked on something and now it's not working, I suggest disabling any recently installed extensions and check if the problem persists.
5. Check the current PHP version and compare it with the previous version.
6. Enable Debug mode and Error Reporting to check if there are any issues.
7. Check the console if you have any editing issue of Page Builder addons
8. Create a staging site before updating anything and check if everything works fine there.

How to create a staging site https://drive.google.com/file/d/1ms8hPQfM3xfF4XUO0W4pUZAhzGUqxBwD/view

• Create a subdomain from your cPanel.
• Export your existing site's database from PHPMyAdmin.
• Create a new database.
• Import the existing database to the new database.
• Update the configuration.php file.
• Go to the administrator section of the staging site.

-Thanks