Disk quota being reset constantly

Webmin
1
SYSTEM INFORMATION
OS type and version Debian 13
Webmin version 2.6

Hello,
I cannot set new disk quotas for webmin users. They get reset constantly (maybe every day ?)
When I change from default 2Gb to 10 Gb for example, it’s saved, and when I come back a few days later it’s back to 2 Gb. For all users (except the ones with unlimited by default).
I had this issue on another server several years ago, and I disabled disk quotas completely because of that.

3

Looks like this happen every day, maybe during the night, quotas are always reset to 2gb. What can cause this ?
My debian installation is recent, and I didn’t make any significant changes. Just installed webmin/virtualmin with official installation script, setup a few servers.