A UKGC licence is the baseline, not a guarantee of a smooth experience. Compare...

https://www.bookmark-friend.win/good-uk-slot-platforms-are-easier-to-judge-by-the-details-than-by-flashy

A UKGC licence is the baseline, not a guarantee of a smooth experience. Compare published RTPs, check withdrawal timeframes and look for accessible deposit limits, time-outs and self-exclusion