AIFF detection marks as fake

[Ves]

I've converted 5 files from WAV to AIFF and 1 of them comes up as being fake. I used iTunes to convert it to AIFF as i've read from a few reports this was the best software to use to covert to AIFF. (Did it twice)
When I convert it to FLAC or MP3 (LAME) using Audacity it is marked as good.

Could you explain how that is possible. I'm able to share the WAV if needed.

iTunes settings

WAV

FLAC

AIFF

[Fake No Funk]

As you can see from the pics, the wav and flac version show a fully qualified spectrum up to the end of the frequency range. The AIFF version not, there is a cutoff at some point (can't read that number, the image is blurry).

According to the heuristic when scanning a spectrum, the app would not expect this for highest-quality files,

If you feel that this is an error, use the option "allow cutoffs above xxxx Hz" (e.g. 20 kHz) and it will not be marked as fake.

I don't know how this AIFF encoder works and why it cuts off the high frequencies..

[Ves]

The line is at 20,735.

Thanks for the explanation. My journey to understand things better continues.