The UK didn't scrap the Interchange Fees Regulation; but as a matter of law there became two separate IFRs, one covering the EEA-cards-in-EEA and one covering U

The UK didn't scrap the Interchange Fees Regulation; but as a matter of law there became two separate IFRs, one covering the EEA-cards-in-EEA and one covering UK-cards-in-UK (To put it bluntly, a big amendment was automatically applied to most UK laws on exit day replacing EU & EEA with UK; and of course in the EU the definition of both of those words changed)