Thanks @t.lamprecht you were right. Changing mounting in fstab on pve node solved that one.
updated fstab works now correctly also on LXCs via binding
/dev/sda1 /media/disk1 exfat uid=1000,gid=1000,defaults 0 1
Thanks for quick support !
I did in place upgrade from 5.x to 7 and after that my HDD on LXC bind as mp became suddenly read only.
On host I can access mounted UBS drive and write to it as root.
On LXCs (priviliged) mp setup did not changed from 5.x, they have no "extra" options added from my end but they suddenly...