red bar next to health bar, bug?

Is this a bug?
Doing a Bleed/Incision/Companion build on Huntress, also fighting against bleed.
I haven't noticed this red bar on other playthroughs with other characters.

If its intentional idk what it's for, it doesn't move, just appears and disappears periodically.

Consider making a green health bar decal over the Companion if that was it's original intent. It could be an issue with bleed, or I'm just dumb.

*picture disbanded, reuploaded, incase you didn't see it

Herald of Blood causes that thing apparently, are you using it?

https://www.pathofexile.com/forum/view-thread/3754471

Yeah, same thing. I guess it’s tied to Herald of blood