Interesting. Maybe it's a demographic blind spot? I do all of my UK banking on Transferwise, and so have heard of or researched Revolut, N26, Monzo... In fact, I think that both Monzo and Transferwise are UK based, and I've definitely seen their ads in the tubel, know people who work there, etc.

They also offered a solid metal card and lounge-access perks, so I suspect that their core demographic are young-ish "digital nomads". Maybe that's where most of their marketing went to?