What I expected to happen was...:
normally just a quick clock
What actually happened was...:
a clock of the time for a piston to move wich make sticky piston with a redstone block bug
Steps to Reproduce:
take a sticky piston
put an observer block with his face on the sticky piston
put any solid block on top of the observer block
put an observer block facing the sky by using the other observer block
power the piston
u can break the second observer block
put a redstone block in front of the sticky piston
put all possible piston which could be activated by the redstone block
u get tp 'in' the pistons which move quickly by approaching them
Please check if that's still an issue for you in the latest 1.15.2 stable release.