To end this up:
As players you see game from your perspective, so everytime you see something happening in game you: either think it's a bug or think it's intended and work around it. Sometimes you can't tell if something is a bug unless you ask us. Last example: Lilith + Dance of Shadows. There are other bugs which you know is not intended - like buffing trought Baiums door, because you clearly see restriction for it.
What we see in this case?
From players perspective they noticed that Baium resets his HP after not getting any damage for 10 min, there was another instance of HP reset ( example: QA reset and regen HP to full ), so from players perspective if other bosses + Baium uses same mechanics - it's intended by admins. From our perspective - Baium have his own reset feature and it's going back into stone, using on top of it another reset feature - is wrong because Baium have 2 hours farm timer.
So because from players point of view ( through game ) it's intended ( because Baium + other bosses uses same feature ) and from our - it's not, you can only get clarification if you come to admins with specific question, which not everyone is doing. Some players is adapting to a gameplay even if it's harmed/harming/will harm them.
And in the end - our conclusion:
Baium should not reset if not taking damage for 10 min because his version of "reset" is going back to stone, which is happening after 30 min not taking damage ( only in this case he should regen HP ). Already fixed and installed on live server, will apply with next restart.
Regarding screen: players might see it as intentional work because other bosses/baium him self used it before and unless they ask admins, they can't confirm if it is or not. - I don't see reason for a punishment ( ban ), full blame on us. This issue harmed or could have harmed both sides.
Based on all of that information:
We decided that we don't want to punish both sides by just removing Baium.
We don't want to give Baium loot only to 1 side, because one of them did ~150% of intended damage in order to kill Baium. 2nd side was reacting and changing actions based on current state of Baiums HP and got him at the end.
So both sides got same loot that was dropped.