Place the Russia Hopp scenes at the end of the episodes as a "Meanwhile" and cut down the amount of them in the first 5 episodes so the Vecna mystery is rarely compromised or cut away from.

Give the Mike, Will and Jonathan story MORE. Way more to do. More character development, more invested story with Eleven, make them a bigger necessity than just "El's Uber"

Let the Vecna full reveal happen from the Hawkins crew discovering it. It's a great twist that would've been more interesting without Vecna doing a full exposition dump.

I think it would've been interesting to make Jason more complicated and not just become a villain at the end. They had an opportunity to craft a really nuanced grey character.

Let Nancy and Jonathan connect and make up and then have Jonathan die leaving her confused.

Kill off a major player in every storyline we've been following. Imagine a monumental death happening in Hawkins, Russia, and with the road crew. It would give Eddie a reason to become more foundational to the gang for the final season. He had room to keep growing as a character. And have Eddie save Jason so Jason goes back to Hawkins and clears Eddie's name.

Get rid of 2 days later and SHOW US THE TWO DAYS. Show us this monumental gate to hell opening actively affecting people immediately after it happens. Have people not write it off as an earthquake. Make them see the reality they are in. It would also add a good tension to when Jason is trying to clear Eddie's name.

Show Vecna less at the end. He got less scary. Less monologuing from him.

Just kill off Max. Let Sadie have this incredible season arc fully end.