500 error using PHP 8

I am getting a error when trying to access any area of Community Builder:

Sorry, there was a problem we could not recover from.
The server returned a "500 - Whoops, looks like something went wrong."

We are using Joomla 4 with Community Builder 2.8.0. We had been running PHP 8.1. Once I changed PHP back to 7.4 I am now able to access Community Builder. Is it not compatible with PHP 8 or is there another issue?

CB is compatible with PHP 8. Enable debug mode and maximum error reporting in Joomla global configuration then retry as that should show more information about the error. It's usually a 3rd party plugin that isn't compatible causing such issues.

Thank you for the quick reply. Attached is the error I receive when trying to access Community Builder from the backend - using PHP 8.1. Is this plugin related to the old version of Community Builder? 

Fatal error: Array and string offset access syntax with curly braces is no longer supported in /homepages/9/d323186062/htdocs/imtajoomlaj30/components/com_comprofiler/plugin/user/plug_cbantispam/component.cbantispam.php on line 477

It's coming from an out of date CB AntiSpam install. You will need to subscribe and update or try fixing it yourself.

I purchased and installed CB AntiSpam and we are still getting a server error in Community Builder. This is the error that displays now:

Fatal error: Declaration of getcaptchaTab::getDisplayRegistration($tab, $user, $ui) must be compatible with cbTabHandler::getDisplayRegistration($tab, $user, $ui, $postdata) in /homepages/9/d323186062/htdocs/imtajoomlaj30/components/com_comprofiler/plugin/user/plug_cbcaptcha/cb.captcha.php on line 324

I don't see a CB Captcha plugin on the Downloads area of your website. Can you tell me what else we need to do?

In your error, I see "getcaptchaTab". You should uninstall old CB Captcha plugin. It is replaced by CB Antispam, containing captcha features.