Hi!
I was able to resolve my problem by contacting the hosting company. I don’t know what they did but now I am able to edit my old pages.
Hi,
I am unable to activate PHP 7.4 or higher since then I got “Your PHP installation appears to be missing the MySQL extension which is required by WordPress” error.
The same thing happens when I switch to the parent theme – circle spinning forever.
But, I noticed something weird:
When I go to edit the existing page end enable inspect in Chrome I got 404 error for admin-ajax.php file 4 times.
Check the picture: https://ibb.co/0ywFVZ2
This never happens when I go to old post editing or if I make a new post or a new page.
Maybe this can be a clue for you?