Pistons do not behave consistently and may or may not retract when a Redstone signal is passed over a piston facing down. This behavior is dependent on the location of the piston, and the location of the power source on the Redstone line. These budded pistons retract when updated.
Linked issues
Comments 3
Yes it seems to be described in MC-11193. Testing out the glitch in other versions it seems to have been happening since 1.12 (as far back as I tested) to 1.16.3. I wish I saw that earlier because I didn't want to make a duplicate post. It surprises me that this has been in the game since 1.5 and I haven't noticed it since today along with others I showed it to.
Does MC-108 describe your issue, because this is intended