Hi Wayne,
In General SPPB 3x/4x and Helix Ultimate works fine in PHP 8.0.x without any errors.
On offcial Joomla forum I found that topic >> https://forum.joomla.org/viewtopic.php?t=987386
I guess, hosting support help is needed. Or you have old plugin from the past that make that mess.
Do not use PHP 8.2 yet!
Anytime you can install raw Joomla (the same version you have) on the test subdomain, then install this same template and SPPB and import a few pages, for a test and you will see. If it would be OK, then an error is from the old plugin which has to be disabled, uninstalled. Investigation is on your side!