[hopefully not already in the list; couldn’t see it]
The app calculates “what day it is” in two different ways within the same UI — a bug / implementation that only rears its head if you’re more than a few hours away from home, timezone wise.
The headline “You spent £XXX today” at the top is calculated from UTC.
The spending history below is calculated from unadjusted transaction timestamp (I think?!).
Either way, the two figures don’t align which means, for example, I’ve spent £250 today even though it’s lunchtime and I’ve not even bought that yet.
It’s a wonderful bit of design overall, you lot.