Redstone comparator is when right click twinkle by hopper (activity comparator)

Confirmed. How to reproduce:
1.) Add an item to the hopper inventory
2.) Right-click the comparator several times
3.) You will see a very short off-state twinkle every 2nd click

Duplicate of MC-10653, please use the search function to see if your bug has already been submitted. Currently over 57% of tickets are being closed as duplicate.