When using any form of 1 tick clock(eg comparator or observer), droppers and dispensers display unusual behavior.
When placed in the orientation shown in the image below, the first 2 droppers get stuck in the activated state, and fail to properly dispense items.

This behavior is not present in 1.15.2.

In the image(2020-08-11_16.27.23.png) below, the dropper in the circuit only fires once, even while the clock is still running.