I just received my Galaxy S21 Ultra which is my upgrade from the S20 Ultra.
Minimal difference between the devices overall, however I can notice a major difference in the speaker/sound quality.
I've compared both devices and settings to ensure they're the same and I find the S20Ultra is considerably louder.
When gaming there's also a 1 second lag between the device and my new pro buds. I've tried switching the setting to game mode and still no change.
With the S20 Ultra it was the camera crack and now the speakers on the S21 range.