I've upgraded to PHP 8.0.8! I now have access to the JIT compiler, and it does make a big difference to the feel of the site, named arguments, the 'match' expression, the nullsafe and nullsafe assignment operators and loads more cool things, like more recent versions of Laravel.

The process was nearly as seamless as you'd expect, with the only hiccup being a phpMyAdmin white screen caused by curly bracket access to array values being deprecated in an older version of PHP (between my previous 7.29 and my shiny new 8.0.8), but now it's all good in both Apache and on the CLI