I completely agree that this is important.
What I’m hoping this thread doesn’t turn into is “what if Amazon do x, y, z with my data?” which would be a waste of time if they don’t ask for it or do those things & instead, if users have concerns they can ask Monzo to “ensure that they’re protected against x, y, z” because they’re worried about “…”
The difference is that, that keeps the conversation constructive, which means that it gives Monzo ideas that they can act upon. Of course, if anyone would prefer to simply complain in advance anyway then go ahead 
Ultimately I’m not worried because I trust Monzo take good care of my data, see this post & this one, for example but I appreciate the fact that others might not be so confident.