cf. earlier:
do you have any files (besides www.conf) in /etc/php/7.4/fpm/pool.d/ ?
You said something regarding firefly-iii which you upgraded, and apparently doesnt need php7.4-fpm anymore.
Running yunohost service remove php7.4-fpm really isn’t a huge deal, it only removes the integration on the (non existent anymore) php7.4-fpm service from the “Services” list in the webadmin and diagnosis checks …