Droppers does not get powered as before.
In the past, droppers that is powered directly gets powered first, and the other droppers that is activated(refer to powered vs activated) will power later after the first dropper. This simple rule can be used to create a dropper t-flip flop.
However, in recent editions, droppers follows this rule randomly, which means that the activated dropper may be powered even earlier than the directly powered dropper, causing the dropper rule broken.
This bug can be produced as follow: Refer to the picture attached, then place an item at the bottom of the dropper, the update the left observer. There are two possible outcomes: One, the item is now located at the top dropper; Two, the item directly spits out through the top dropper, where this is the bug.
Note:
1. All observers and the top dropper are facing to the right and the bottom dropper is facing upwards.
2. If scenario 2(bug scenario) does not reproduce after a lot of tries, try placing it in other locations or directions.