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I've been experiencing that since they updated the OpenAL library in 1.13 as can be heard in this video. (There's an extra stereo effect due to the MaxxAudio settings I had at the time, but you can still hear the sound frequencies changing when looking up and down.) There's also some bugs such as MC-125155 mentioning a change in sound quality due to HRTF changing the character of the sounds.
The catch was that if the game detected you as using speakers instead of headphones, it will apply a different speaker mode which doesn't have HRTF and also pans the sounds more aggressively. So I'm not sure if they just improved the audio device detection in this snapshot along with adding the in-game toggle, or even added HRTF to speaker mode, explaining why you experienced a difference.