Pistons have 2 heads when mouse is flicked on the edge of a redstone block, with one of the heads being indestructible until a block is placed inside it. Can be replicated.

Video is too large to upload as attachment: https://screenshot-hub.tixte.co/PistonVideo.mp4

Edit:
All screenshots are from 23w04a, but the bug appears in listed versions below:
23w04a, 1.19.3, 1.19.2, 1.19.1, 1.19
Bug did not seem to happen prior to 1.19

Edit 2: 
Main ticket was marked Invalid due to the game version being modded.
For reference, this ticket was done in vanilla versions of 23w04a, 1.19.3, 1.19.2, 1.19.1 and 1.19