Makes me think of TSB who, in the aftermath of their IT meltdown in 2018 increased the interest rate on their current account back up to 5%. It was a “thank you” to their “loyal” customers who had suffered weeks of issues accessing their TSB accounts. The increase was announced much fanfare and a promise that it “wasn’t just for a year”.
14 months later (more than just a year), they dropped the rate back to 3%, and now it will shortly drop to 1.5%.
So yes, if they aren’t contractually bound to do something then it is just a politician’s promise.