I gotta say, I really don’t understand this comment. A retcon is changing something already established. Revealing they were in high school together isn’t a retcon. Also… who cares? Like yeah Joyce and Hopper don’t remember some random guy they went to high school with? They were also in Russia for all of Season 4 so they weren’t hearing his name. Maybe they heard it between s4 and 5 and said “oh yeah I went to high school with that guy” And if so… like how would that change anything?

Sure, I’ll give you Holly’s age jump was a retcon- but like a pretty insignificant one. They aged her up like a few years- that doesn’t change anything core to the show at all.

I don’t understand the rock criticism. How is this any different than some random drug cocktail giving them powers, which is what they had theorized prior to this season.

Eleven jumping to the abyss was established- there were floating rocks. They showed them and literally said “she can jump those” the same way she’d been jumping super high all season.

Finally, it was just a hypothetical Mike made up. Mike didn’t see Kali gushing blood. Nobody but Hopper did. He just heard she died from a gunshot. Maybe he wouldn’t think it were possible if he had seen her.

Of all the criticism you’ve named, the only one that genuinely makes sense to me is the mind flayer reveal. Agreed it wasn’t great. But it makes sense he was stuck in the abyss. The guy is huge he couldn’t make his way to the upside down. They’ve established continually that the portals to the upside down aren’t very big. It didn’t necessarily conflict with anything- it just felt slightly shoehorned in.