This problem is specific to Plesk, they’ve disabled opcache_get_status for some reason.
I think the code will run just fine if you disable the opcache module in PHP 8.0 but you don’t get to use opcache, of course. Note that having it enabled might not mean you were using it, if the php.ini settings weren’t also turned on.
This is were it happens
→ SuiteCRM/SugarCache.php at master · salesagility/SuiteCRM · GitHub
The definitive fix would be to surround that also with the function_exists check that the other nearby bits of code have. The assumption that the function would exist if the module was enabled doesn’t seem to hold for Plesk servers…