That means that the SMMSTORE / NVRAM EFI variable storage is getting corrupted somehow. What platform is this on? I've seen some older platforms which are problematic, especially Braswell, but newer Core platforms seem to work reasonably well. There's also a new SMMSTOREv2 implementation you can try, but requires using the TIanocore UEFIPayload option as well as setting the branch/commit ID to `origin/uefipayloadpkg`