Snapshot Error: Failed Instance Creation .. Got error reading source

Hi all,
i have a daily script that snapshots all my containers into another lxc server using this command:
lxc copy c1 server2:c1 -c boot.autostart=false --verbose --refresh --storage "default"
The problem is that i encountered this error already on 3 containers:

Error: Failed instance creation: Error transferring instance data: Got error reading source

I remove the first two containers facing this error from my script (the script stops on the first copy fail) thinking it was due to the large size of the containers.
But now with the third one i don’t know what to do because i need the backup of this machine and
I would not like to find it in the future on other machines as well.
Thank for any advice

Do you still see this with LXD 5.2?

I’m now on version 4.0.9,
is there any risk (compatibility of containers) in doing the upgrade?
Is this the right way for upgrading?
sudo snap refresh lxd --channel=latest

The latest LTS version is LXD 5.0 using snap channel 5.0/stable but it will not allow downgrading, so I would advise trying to reproduce the issue on LXD 5.0 or LXD 5.2 on a separate machine first to avoid impacting your current install.