It looks like the app starts FaceID scans on its own again , but now it seems the app doesn’t automagically log out anymore if you leave together open when backgrounding?
What happens is that when foregrounding the app, to my surprise it didn’t prompt for FaceID whilst I had it backgrounded well beyond the timer. As soon as I tried to open another tab: it did suddenly logout and prompts for FaceID/code.
So it isn’t insecure perse as it does seem to log out when trying to access anything else, but it is inconsistent behaviour.