Observers are inconsistent on when they provide the power pulse after being pushed by a piston

When an observer and piston are pushed and pulled by a sticky piston receiving a one tick pulse, Sometimes, the pushed piston fails to extend despite the observer also being pushed

To reproduce the bug:
1: build the pictured contraction
2: Make the lower left observer observe an update (placing a block works)

I expected the sticky piston would push the slimes and piston, the normal piston would activate, and the sticky piston would not pull the slimes and piston back.

But, sometimes the normal piston fails to extend on time, and the slimes and piston are pulled back