An Event Trigger attached to a UI Canvas button causes the associated UdonSharp script to receive the event more than once per mouse down.

If the canvas is on the UI layer, this event is triggered 2 times per click. While if the canvas is on the Default layer the event is triggered 3 times per click.

This behavior is only seen within the VRChat Client Simulator in Unity, and does not happen on built worlds within VRC itself.

Demonstration in Unity: https://i.imgur.com/2h8yEJn.gif (Clicked 4 times)

Demonstration in VRChat: https://i.imgur.com/5g9y6PS.gif (Clicked 3 times)

Minimal reproducible example: https://drive.google.com/file/d/1bJtUSqUwvvoWQAdK9JtaNn_0qGYrLa8U/view?usp=share_link