Earlier quoted context omitted.
The problem (for the bank) is they are now liable in the UK[1] if you are defrauded because someone installs malware on the phone. There's basically zero upside for the bank to allow customers to use F-Droid, since probably 0.0001% of their customers would do this, compared to a vastly greater number of customers being tricked into installing random malware on their phones. Accessibility settings are a tricky one sin…
From the bbc article, the number of fraud rose 12%, and you're presuming 0.0001% would be using F-Droid. Is preventing that an efficient ("reasonable") action from the bank ?
Number of people using F-Droid + a banking app is approximately zero in comparison.
There is not the slightest chance in hell that taking on the legal risk from F-Droid users is a sensible use of the bank's resources.
Sources: https://www.nationalcrimeagency.gov.uk/what-we-do/crime-thre... https://www.nationalcrimeagency.gov.uk/threats-2025/nsa-frau...