As somebody who lives in the UK (London area), I've never even heard of this company N26, let alone aware that they had UK operations. I do frequent the web, youtube, bus stops, tubes, trains and utterly exposed to all forms of marketing. So from my perspective, this does seem like marketing failure from the start - at least from my perspective. Though the only real new Bank in the UK to do well, traction wise would…
This probably indicates that you are not in fact as well exposed to bank marketing as you suspect - it's hard to argue that Monzo and Revolut have not done well.