Wrong, PHPSwitcher even support PHP8 (installed on Debian 9.x, but not in used yet).
You just have to search in the forum, but you can change what version the plugin look for.
Any hint for the search terms?
I've got all from sury related to PHP8, but
perl /var/www/imscp/gui/plugins/PhpSwitcher/PhpCompiler/php_compiler.pl --register --packaged --packaged-only
only updates up to 7.4.