UK online casinos operate under tight rules set by the UK Gambling Commission....

https://www.bookmarking-online.win/uk-online-casinos-operate-under-strict-rules-set-by-the-uk-gambling-commission

UK online casinos operate under tight rules set by the UK Gambling Commission. These rules include things like a minimum return to player (RTP) of 96%, which limits how much the house can win over time