Paying a cheque in is inaccessible. It requires you to hold your hands steady and use Monzo’s custom camera widget - it should allow you to use scans of documents rather than a photo, select from your gallery or at the very minimum use the native camera app instead of reinventing the wheel.
Plenty of people, especially as they age, have difficulty holding their hands steady enough for this to reach whatever standard of clarity Monzo require. I say this after having one declined that looks pretty clear to me, so it could just be a broken feature. Regardless of my experience, the issue remains.
I’m all for making things more accessible, however we are talking about dealing with money, and is very susceptible to fraud. Monzo building something native to their app means they can control every aspect. Allowing external camera access or document upload opens them up to more fraud attempts, so they probably don’t want that risk.
While the in-app feature might not be suitable for everyone, it’s not your only option for depositing a cheque as sending via FREEPOST is still there for you.
Yes and Creation Finance’s (whom Apple now use) app was awful when trying to scan my driving licence. It needed the tiniest micro adjustments of phone position in 3D space above the driving licence to get it to actually take the photo.