With MC-251518 fixed, the allay's wings flap faster as the allay moves faster. As the allay's velocity increases, the wings start to converge on each other, eventually clipping through each other. The issue becomes even more apparent when the allay quickly flies back to the assigned player or note block.

The issue can be identified more easily by looking through an allay's point of view through spectator mode and using F3+ESC to pause the game and be able to see the allay's wings clearly.