Session expired or cookies are not enabled

Error:
[Session expired or cookies are not enabled in your browser. Please press "reload page" in your browser, and enable cookies in your browser.]

This error has come up a number of times over the years, most recently about four months again, which was attributed to a caching issue.

Normally the form returns a green "The username 'username' is available." or red "The username 'username' is already in use." message.

For the last two days, the error has consistently occurred on every platform for anyone trying to fill out the registration form regardless of cookie settings or page reloads. It also does not matter if the entered username is available or not. Furthermore, clearing cache did not fix the issue.

Recent changes include a server upgrade about a month ago with a move to PHP 8.2.

Joomla 4.2.2
CB 2.7.3+build.2022.09.26.13.53.56.486969333
PHP Version 8.2

Do you have Joomla's page caching plugin enabled? Our form tokens are entirely Joomla driven now so we're just passing them to Joomla. Typically the only reason they fail now is page caching or similar 3rd party caching extension.