I run Apache 2 Magento 2.4.2.p1, and I've installed magento properly, even added a theme without any problems. However, suddenly, I ran into a permission issue when editing my theme's configuration. I googled for solutions, found out that when you import themes through ftp, the permissions have to be set for those new files and ran the commands:
253 sudo find var generated vendor pub/static pub/media app/etc -type f -exec chmod u+w {} + 254 && sudo find var generated vendor pub/static pub/media app/etc -type d -exec chmod u+w {} +
chown -R magento:www-data .
This seems to work as my user "magento" is back to being the owner of the directories and files, however, when I went to my website, it would output a "Error 500" that was not present before running the commands. I searched for a solution to this new problem and found out that you had to run bin/magento setup:upgrade. But, for whatever reason, something is reverting the ownership of the files that are being generated such as the cache to the "root" server user.
TL;DR: magento doesn't have permissions to read files that were imported via ftp --> I try to give it ownership of the files --> get error 500 --> run setup:upgrade to try and fix error 500 --> > files' ownership is set back to the root server user -- error 500 stays
