Available / used GBytes wrong in WebDAV davfs drive

I've mounted a WebDAV cloud drive (storage / remotemount / davfs) to dump my borg repo and NVR files there. Works fine.

From the beginning the available / used GBytes shown in storage > file systems are stuck to "508.63 GiB / 762.93 GiB" (total 1 TiB).

These values have not changed for weeks, while the drive has now approx. 200 GB free, 824 GB used.

df | grep remote
https://webdav.smartdrive.web.de  1333333332  800000000  533333332   61% /srv/remotemount/web_cloud

Probably it's the providers fault; "rclone about" has no output.

du works fine.

As workaround I run a script every hour calculating the values by myself to get a warning when the available free space drops too low.

I'd really like to "overwrite" the wrong values with my calculated ones esp. in the dashboard widget.

Any ideas?

Ok, thank you for the explanation. I'll live with it.