I had to buy extra data for 2 months in a row for my mobile plan because of excess data used by nextcloud
Is it v3.30.1 of the app?
Itβs v3.30.3
How much data do you have in your Nextcloud? You can find this under Administration β Server β Disk.
I have 144 gb
So this means you got caught by the bug mentioned by user jtr above. The fixed versions were released just 2 weeks ago: