I asked the hosting provider he told me this error may be due to this..
According to my check, the following error triggers in your domain error log after the registration attempt:
[01-Dec-2022 23:45:44 America/New_York] PHP Deprecated: strlen(): Passing null to parameter #1 ($string) of type string is deprecated in /home/examsvrl/linkif.org/qa-include/qa-theme-base.php on line 661...
Sometimes the website is not compatible with the PHP version, and it can cause the issue.."
Please help me out?