I don’t think notifications and top–ups are comparable. The former is a genuine, useful innovation for a bank account. The latter is just another way of doing something you’ve always been able to do for free, which costs more.
Anyone who insists on using top–ups, and paying for it, when the existing method has existed for years, and is no more onerous than a couple of taps, needs their common sense reset. I mean, soon it’ll even be cheaper to write yourself a cheque and scan it into Monzo than it will be to top–up.
I feel sorry for Monzo a little bit. In the rush to assure people that nothing bad would happen when they converted from pre–pay, they’ve ended up with a moral liability which costs them the difference between profitability and loss, and which no–one really needs anyway.