I lost my password to the (only) kirby user. After removing the folder from site/accounts/ I can install a new user and set a password (only one field). If I submit it throws an error pop-up that “The passwords do not match”. I am a bit lost here as there’s nothing the single entered password can be matched against?
Support for PHP 7.4 was added in Kirby 3.3.2, you are running an older Kirby version, so this is most likely the reason why you are running into this issue now. You would have to either downgrade your PHP version (although that might not even be possible and would be quite risky, considering that even PHP 7.4 is reaching EOL in a few days). Or upgrade Kirby to at least 3.3.2 (we are currently at 3.8.2).