Sorry to hear you are disappointed about the direct email. To explain, support hasnt changed. We are simply doing it in a different location. We still have access to your details, we can get to a private ticket if needed etc. So nothing really changes in terms of the support you get there.
With the issue in question, firstly I would advise on checking the requirement checker, to make sure after switching you have all the elements needed on your PHP installation.
I would however suspect this is the case, as you managed to upgrade. So the next (very) likely cause is that you have a 3rd party item which is not compatible with PHP 8. Please disable all 3rd party applications and then check again. You can do this by running recovery mode, as seen in the guide here