Corn_Pig that extension generates an error in your logs: flarum.ERROR: TypeError: floor(): Argument #1 ($num) must be of type int|float, string given in /data/host/skeleton/vendor/foskym/flarum-custom-levels/src/Listeners/GiveExp.php:75
I think you have misconfigured the extension, or there is a bug in that extension. In order to check this, can you please show me a screenshot of that extension’s settings in your admin panel?