I recently got my girlfriend onto Monzo. Every time she wanted to enter the app and had to get a the email magic link sent to her. I found that strange, and then a few days later discovered why.
She was logging out of the app every time after using it. She was doing this because that was what she considered the right thing to do.
This might be a rare thing, but maybe the UX needs to be improved, or Monzo could contact individuals that keep logging out to make sure they understand that it is not necessary. I’m sure Monzo is collecting metrics around this sort of thing so they’ll have some idea about how many customers it affects.