Rsync to TrueNAS failed lsetxattr with operation not supported (95)

I created a Dataset and a share on it and was able to mount it with mount -t- cifs on my client machine, which is an ubuntu 24.04 LTS. I configured the app Kup to backup my files to this share on TrueNAS. Backup starts and copied a lot of files when suddenly the rsync stops on error. In the log I can see:

rsync: [receiver] rsync_xal_set: lsetxattr(“/media/cifs/Backup/Zuse24…/.ydcdsx4ov31v”,“user.Zone.Identifier”) failed: Operation not supported (95)
rsync error: some files/attrs were not transferred (see previous errors) (code 23) at main.c(1338) [sender=3.2.7]

Can someone explain what is going on here. To my opinion extended attributes are supported by TrueNAS but I am new to ZFS and TreuNAS so I might have missconfigured something.