mysql 8 support
Jamroom should run no problem on MySQL 8 - I develop on it and don't see any issues (currently on 8.0.35). Are you sure it is fully installed correctly and that it's not trying to bring in any of the previous Percona install? One thing that might be worth a shot is add this line to your data/config/config.php file:
$_conf['jrCore_sql_mode'] = '0';
Just in case it was installed with the sql mode set to something weird - this will disable it. Not sure if that will help or not but worth a try. Let me know if that helps.