Why /sys/devices/.../product_serial sometimes reads as garbage?

Service reads sys/devices/virtual/dmi/id/product_serial somewhere at start and generally it contains some typical hex number of ten digits (e.g. 01212302C5) with newline. However sometimes the content is not parsable to string - bytes in hex are f8 6a 32 6d 0a and I can't figure out why and how this happens. The last 0a seems to hint it still was supposed to be text. Happens generally in CI but I'm not sure may containerized environment somehow be the reason of the issue. What could be the reason of such a queer behavior?