I have added First Direct accounts to some of my Monzo contacts. Due to their affiliation with HSBC, Monzo displays an HSBC logo instead of a First Direct logo.
Is there any way to fix this?
No.
It’s not merchant data (like the link above) but some other form of table that Monzo have embedded somewhere.
There would be a way for Monzo to do it if they want to up-issue the app and there is a request thread around talking about it but I don’t see it happening any time soon.