Is "file" backend safe for production or not?

This line of the FileBackend reads:

// FileBackend is a physical backend that stores data on disk
// at a given file path. It can be used for durable single server
// situations, or to develop locally where durability is not critical.
// WARNING: the file backend implementation is currently extremely unsafe
// and non-performant. It is meant mostly for local testing and development.
// It can be improved in the future.

Does this warning mean that the file backend will randomly scramble the database?

The documentation seems to imply that file is safe for a single-node Vault instance.

Is the file backend safe for production usage or not?