Sander I don't know for sure because I have no clue which icons are already in the app and which ones aren't. So I mostly choose "don't know" unless I know it is a shop with only 1 location then I can easily select "no". TBH I find this a strange question anyway. Unless I've paid at several locations of a big chain I can't know if their logo is in the app or not.
I don't know if a public repository would work. Someone has to keep an eye on all the icons to prevent them being switched to cute cat photo's.
And I'd guess that you'd then run in more trouble regarding rights on the logo and companies not wanting that they are somewhere on a public repository with no copyright and so on. I suppose this is already a gray area but because the logo only lives inside bunq not many know/or are bothered.