Observers are placed with the input facing you (unlike MCPE)

The MC Java edition counterpart of MCPE-17321. Placing an observer block in the Java edition places it with the observing side, or the input, facing you. In MCPE, placing an observer places it with the output side facing you. I'm not sure whether this is a Java edition bug or an MCPE bug. Since repeaters and comparators are placed with their inputs facing you, I think this may be WAI, in which case it is MCPE that needs to change.