I’m not sure if Monzo can know this (with the exception of foreign currency purchases, which are clear-cut). All transactions are pending for 1–3 days. The risk of falsely identifying one as something that will change seems like it would cause more confusion.
It’s things like this that show how much we need a modern payments system (or two) that don’t rely on ‘hacks’, which is what using pre-auth in this way seems to be.
The main issue for me isn’t really identifying those that may change amounts. Knowing which transactions are pending will help you know whether you have to pay overdraft fees or not.
Yeah, I can see that it would be better if Monzo clearly showed what your balance is from an overdraft perspective. I don’t know how they can solve this design-wise without ending up in the ‘available balance’ nonsense of legacy banks, but it is an issue that should be addressed.
I’ve never used a pay-at-pump, but my understanding from discussion on this forum is that sometimes these show up as, for instance, Tesco, and so it’s not always possible to identify petrol from groceries. Or has this been fixed? If so, I agree it would be a good idea to grey out until settled.