It's invalid (closed) for MATE (not really MATE's issue), but not necessarily invalid for Deja Dup.
Looks like you mostly have incremental backups there. Deja Dup will make a new full backup every 3 months. And incremental backups in between the full ones.
It always wants two full backup chains (full + following incrementals) around, for safety. But any extra, it will delete as needed.
You may just not have enough space on your drive for a full two chains?
It's invalid (closed) for MATE (not really MATE's issue), but not necessarily invalid for Deja Dup.
Looks like you mostly have incremental backups there. Deja Dup will make a new full backup every 3 months. And incremental backups in between the full ones.
It always wants two full backup chains (full + following incrementals) around, for safety. But any extra, it will delete as needed.
You may just not have enough space on your drive for a full two chains?