The opposite, the app asked for a frame rate of 24.000Hz but got a frame rate of 23.976Hz.
Apple's frame rate API is a request, you might not get what you asked for. The reason is there is no public API that returns the possible display frame rates. But you can see them in the console log when a hdmi device connects and the EDID is probed.
Apologies, I meant the opposite! So yes, it’s outputting 24p when it should be outputting 24hz for some media. Oy... Apple, jeez...