I had the same problem migrating my server to Debian 12 with PHP 8.2
I fixed this replacing :
if ( strrpos( $url, $white_url, -strlen( $url ) ) !== false ) {
With
if ( strrpos( $url, $white_url, -strlen( $url ) ) !== 0 ) {
At line 1144 of the classes/wp_cassify_plugin.php file.
Maybe the plugin should be patched, but I don’t know if it still maintained ?
