It's a feature. You want to be able to read it in the future even after a disaster has struck.

What would be a bug is if it was easy to find, or if it was easy to reveal.

A lot of plates have a cover or are placed in tamper evident containers or sealed with tamper evident seals.

Typically you should know it is hidden well enough to never be found, or you should keep it somewhere private but accessible and check that it's tamper seal has not been broken or compromised from time to time.

Finding that exact line between hidden and monitorable is something everyone needs to figure out for themselves.