I actually tried what you suggested and it went up to 2.41gb - up from last time.
I don’t understand why the download is so big.
The reason I noticed this was because I recieved an email from Apple about my iCloud storage. I’m just going to have to prevent it updating if it means I run out of iCloud space. I refuse to give Apple any more of my money.
All Monzo data is stored on Monzo servers, so there really isn’t any need to keep an iCloud backup of the app database. I have Monzo app backups turned off (as well as app backups for other service apps).