SP

Resolved.

1. There isn’t a front-page.php file under the twentytwentyfour theme folder.
2. I managed to remove the “front page” template in Site Editor mode under the “Manage all templates” menu.

Interestingly, it appeared that I had unintentionally created a front page template in the site editor. I’m still uncertain how or when it was created. I just assume that it’s possible that there’s a default option that automatically generates it when certain options are switched.

Well. I found that if I clear all my browsing history and cookies and caches, it simply works…

Thank you so much! It works!

I just contacted my hosting company and solved the issue.
What I did was adding the following line in a .htaccess file and put it back into the root folder, and it just works like there hasn’t been any problem.

php_value max_input_vars 10000

Thank you!