Drupal 7.x

Hello
Sorry about this, but I am working with Drupal 7 and i'm in trouble...

I activated the "Stylizer" and "Colors" modules.
After i did that, the edit article page is different: Now I have more fields, and some buttons doesn't work - i cannot change from plain text to php editing, for example. I deactivated the modules, but the changes persist...

I am searching about it and trying solutions, but I cant understand what happened. I assume i have different codes that conflict with each other.

Heya! I'm working on a project for a client who is using Drupal 7. Among other things, we want to perform an audit of the content currently stored in their Drupal instance. Specifically, I want to create a list of every page / link on the site and any related files / downloads that Drupal is managing for them. 

Looking at the APIs, I honestly have no idea where to start here. I am also digging around the database and, while I see the nodes and various field_ tables that seem to have the content stored in them, I see no obvious way they're connected. 

.. is it as cumbersome and painful as when I looked at the work and upkeep to v8 some years ago?

I worked on Drupal professionally since v4 and have had to ignore it since v8. That version absolutely killed the CMS due to the high maintenance overhead, dependencies, and bloat. I could never recommend it to clients, let alone convince anyone to use it after v7. Against my recommendations, the few that did immediately found their maintenance arc (and cost) explode and their site performance lag.

I have set php to 7.4.33 for the D7 domain which, according to https://www.drupal.org/docs/7/system-requirements/php-requirements-for-drupal-7 , should be OK for D7 version 7.71. But running the install program I get a 500 error.  The database is MariaDB 10.5.22.