Currently on https://docs.moodle.org/401/en/Step-by-step_Installation_Guide_for_Ubuntu amongst the other dependencies listed is libapache2-mod-php

However, at least for me (Ubuntu 20.04) this defaulted to pulling in libapache2-mod-php8.2, which doesn't match up to PHP7.4 like the rest of the recommendations and prevented Apache from starting up. I'm not certain whether everything should now be 8.2 anyway after https://tracker.moodle.org/browse/MDL-70745 (sorry, very new to Moodle, just trying it out!).

Do feel free to steer me in the direction of the relevant repo if it's something I can sensibly fix myself.