Low Bullseye behaves strangely in Boss Instances (already applied on 2nd run)

Description of the bug:
If you hit a one-phase boss with Bullseye, kill it, and then re-enter the boss instance for a 2nd run, it will sometimes spawn with the Bullseye debuff already applied.

EDIT: https://www.youtube.com/watch?v=UJOEECiBBxU

What is supposed to happen?:
It should not spawn with the Bullseye debuff

Where did you find and/or notice this bug?:
Bossing after the patch containing the fixes to the buff system

A step-by-step guide to re-producing this bug:
- Be in a one-phase boss instance (JC is the worst offender but I've also seen it happen in Pap and Rav. Likely also happens at Latanica and Dunas but I haven't checked)
- Hit the boss with Bullseye and proceed to kill it normally
- Re-enter the boss instance for a 2nd run without hitting anything else with Bullseye in between
- When the boss spawns, it will sometimes already have the Bullseye debuff applied

Extra information:
It's intermittent, I don't think I can produce it 100% reliably but it's not a rare occurence. I think it may happen if you re-enter the boss instance quickly but not certain. It's possible it also happens in multi-phase bosses; say you hit b3 of Verga with Bullseye and do not hit b1 or b2 with it in the following run, b3 may spawn with the debuff but I'm not sure.

 

I GOT IT ON VIDEO. Was recording a boss vid for Mr Ainz and just noticed the glitch happens in the recording

https://www.youtube.com/watch?v=UJOEECiBBxU

As you can see, I kill the light ball thing, Pap spawns and already had the debuff

 

Some updates

1) This happens 100% of the time in Boss PQ. Hit the first boss with Bullseye, and all subsequent bosses will also have it. (Normally the first boss I tag is Leviathan; afterwards, Griffey, Pap, and Pianus will all have it as soon as I spawn in)

2) What is my bird doing https://youtu.be/M2G1wJkHvbs

3) No seriously what the fuck is my bird doing https://youtu.be/2_-iy0XgRcI