Repeaters gives an Output when an Observer is retracted from them or the Redstone line in front of them when the Piston is powered by a one tick Pulse. Comperators are not affected by this.

What I expected to happen was...:
The Repeater should not give an Output

What actually happened was...:
The Repeater gives an Output, despite the Redstone line in front of it not being powered

Steps to Reproduce:
Follow the steps in this video:

https://drive.google.com/file/d/12ARdTFvrL21kHQXGN-Eh8jLMG-yOTAjT/view?usp=sharing