@sebastian-roth See above post, sorry, replied to the OP instead of you.

Unfortunately the install still failed. I thought this might just be a bug with my particular server, so I set up a brand new server just for Fog, using Debian 11, but still got this exact error.

OK
 * Backing up user reports.....................................Done
 * Stopping web service........................................Failed!
OK
 * Setting up Apache and PHP files.............................Failed
   ###########################################
   #                                         #
   #      PHP Failed to install properly     #
   #                                         #
   ###########################################

   Could not find /etc/php//fpm/php.ini!

You can view the error logs in this gist:
https://gist.github.com/asheroto/c10799f8ef3ca9ff666853c9ef196642

@Sebastian-Roth Just ran into this issue myself. I found several forum posts about it.

Using Debian 11. Just installed it a few weeks ago.

PRETTY_NAME="Debian GNU/Linux 11 (bullseye)"
NAME="Debian GNU/Linux"
VERSION_ID="11"
VERSION="11 (bullseye)"
VERSION_CODENAME=bullseye
ID=debian

I installed php-php-gettext thinking it might help…

Used ./installfog.sh -X to bypass it.

Just wanted to report the bug exists. Just downloaded Fog a few minutes ago.