Impossible to log in after Sonoma 14.3 update

Hi, I just recently updated my late-2014 iMac (iMac 15,1) to Sonoma 14.3 (it was previously running well on Sonoma 14.2).

I updated it via System Settings. OpenCorePatcher detected the update and prepared some stuff in the background. It all went smoothly until it rebooted and now I’m stuck on this grey log-in page. Even if I write my username and password, the iMac rejects them all the time and I’m unable to log in.

I tried to reinstall the OS via a USB booter but I still have the same problem. I can’t log in with my credentials to install the post-installation root patches. I’ve tried a lot of stuff online based on some users’ log-in issues over the past few months but nothing worked. Even booting in Safe Mode, I still have the same problems. Do you guys have any ideas?