Subtraction comparators sometimes update their output one redstone tick earlier

A comparator in subtraction mode can update its output one redstone tick earlier than expected.

This happens when a weaker redstone signal is sent to the side input one redstone tick before a stronger redstone signal that is supposed to be the subtrahend. The weaker signal must be the one sent one redstone tick earlier. Otherwise, the resulting output would legitimately change, and this would not be a bug.

I would expect the following behavior (in redstone ticks):

1. The weaker redstone signal arrives at the side input of the comparator

2. The stronger redstone signal arrives; the comparator outputs (input - weak side input) (in the same redstone tick)

3. The comparator outputs (rear input - strong side input)

But the actual result is (again in redstone ticks):

1. The weaker redstone signal arrives at the side input of the comparator

2. The stronger redstone signal arrives; the comparator outputs (rear input - strong side input) (in the same redstone tick)

If you don't send a weaker signal one redstone tick earlier (as intended), the behavior is as expected (again in redstone ticks):

1. The stronger redstone signal arrives

2. The comparator outputs (rear input - strong side input)