Repeaters and comparators only give out block updates in case a solid block is in front of them.
Powering a dropper/dispenser or piston like in picture 1, which was possible in all previous versions, is no longer possible, because the dropper/dispenser/piston doesn't receive the information, that it is powered.
Powering only a single piston (picture 2) would be no longer possible without workarounds.
Placing a block in front of the repeater wouldn't work, because it activates both pistons (picture 3)
Grum added a comment - 2 hours ago - edited
This happened when we made the observers not be able to power the airblock in front of them and thus being able to power the observer line with a gaps in it.