Kai, out of curiosity, is there an app that depends on being able to
enable FIPS mode?
--Juan

The only real-life implementation I know about using the flag and actually implementing FIPS is the MS .NET framework. Any application making use of functionality in the System.Security.Cryptography namespace will be limited to algorithms allowed in FIPS if the setting is enabled. You can try this by enabling FIPS on Windows and playing Terraria, for example. In this case, the application depends on FIPS mode being disabled.