A few first time setup steps are missing from the Docs.
I noticed when using PixelFed with Cloudron the admin panel links were missing in the new UI and you couldn't edit the Discovery page (which is done outside of the admin panel).
To get everything working with the new UI, these commands need to run followed by an app restart:
sudo -u www-data php artisan cache:clear sudo -u www-data php artisan optimize:clear sudo -u www-data php artisan optimize
Then restart the app. I hope this helps someone and hopefully gets updated in the docs.