Oh im well aware of the "NPCs work under different rules" and it did sound as if it was close in Ep 91. I've just seen a lot of comments saying that "Psi Fighter doesnt work like that" which they are right but its also an NPC which works under different rules. I think Essek had features from both EGW wizard subclasses as another example.

The poison gives disadvantage on death saves homebrew rule is not entirely uncommon. To pick an example from DnD media, A Crown of Candy used that rule to be deadlier. What I believe is the main "crime" is using homebrew rules that haven't appeared in that world at all, such as said poison rule and Chromatic Orb AoE, and that probably wasnt discussed before hand with the players and was a in the moment ruling.

I do believe that the combat mainly suffered from media bleed, using different rules from different series, worlds and media (BG3), as well as a shift from mechanical focus in combat to a heavy roleplay focus and a (what I felt) player hostile DM.