Visa for example, plan to increase the interchange fee on digital payments made between European customers and British businesses from 0.3% to 1.5%. Other providers will surely follow.
Still lower fees than in the states but probably not for long.
No, they are absolutely still capped in the UK. The IFR regulation has been mirrored in the UK so the same caps still apply to UK cards and UK banks.
The exception you are referring to is when a UK card is used for an online ("card not present") transaction at an EU merchant. In this case it is now considered an inter-regional transaction and a higher cap applies: 1.15% for debit and 1.5% for credit cards. (but note, even here there is still a cap!)