Really not enough information to go on here. I’m not familiar with unraid, but can you add restart: always to the compose file for these containers? Does it have a compose file?

If you’re sure it’s not a memory issue (and it would be a bit odd for the OOM-kill to kill a bunch of containers like this), it could be an IO issue. A hard drive dying, maybe, but I think unraid should let you know about that?