Minecraft: 1.17.1
Mod: 2.0.1

When wearing a Turtle Shell the "positive potion effect gained" sound repeats multiple times.
This is due to the fact that the way Minecraft handles the Turtle Shell's water-breathing mechanic is by giving the player the water breathing effect for 10 seconds and then repeating until the turtle helmet is removed.
This causes the "positive potion effect gained" sound to play rapidly from the sound events caused by the turtle shell.

The same issue occurs with Dolphin's Grace.