The bug
Since the fix of MC-13626, one would expect the level up sound not to play in creative mode.
To reproduce
Set a repeating command block with the following command:
/summon experience_orb ~ ~2 ~ {Value:10}
Stand by it whilst on creative mode.
Expected result
The level up sound ("Player dings") would not play.
Observed result
The level up sound ("Player dings") plays.
i can confirm it in 1.17.1 too