Time Machine detected that your backups can not be reliably restored.

Time Machine detected that your backups on “DISK” can not be reliably restored.

I received this message today on a drive that has years of Time Machine backups on it. The backup is hosted on a QNAP NAS with an allocated portion for Time Machine. The only option Time Machine gives me in preferences (Venture 13.5) is to Erase the backup history and rebuild. Given the significant history here (this was inherited from a prior computer) - before erasing and rebuilding I'd like to try to repair.

I can't find good information on this error message - I assume it is some sort of file corruption? Does anyone have information, and before I wipe and start over are there options to repair?

I can wipe and rebuild, just would prefer not to unless it is the only restore. I did find the "TimeMachineMechanic" utility, but I don't know how to make sense of the logs. I did confirm I can mount the TM backup over SSH (which I believe is the same way TM does in the background) and I can see the file structure - so I do not believe this to be a network issue (although it could be some sort of permission issue perhaps). Is there a way to confirm the TM backup is mounting correctly?

Thanks in advance.