I seldom write a complaint anywhere, normally choosing to vote with my wallet. But not today. Your new UI is such a disaster and forcing it upon so many previously happy customers is a tragedy. Not only is it ugly (subjective, but no light mode, are you kidding?) but it's terrible from a UX perspective (non subjective).
I'm giving you two months to fix this (all of it, not gradually), or I'll switch to one of your competitors. Let this be a lesson to your overly enthusiastic and overly excited UI/UX Team to take it easy and gather some REAL customer feedback before releasing such a travesty into the wild. Also, since bunq is a startup priding itself with moving fast, move fast now too - just backwards.
And to whoever thinks this "isn't that bad", it is. This is Apple Maps bad.
If you think this UI can be "improved gradually" to fix "minor issues", you're in for a surprise: it can't, roll it back. And maybe take consequences - even the might Apple did, and you're no Apple.