YELENA | NATASHA
Well. I'm going to tell you a lot of things that some others might say that is too harsh for you to know but we dealt with Dreykov, so none of it is too harsh, IMO.
The good news is that in my world, you managed to beat Ultron, but there are always new bad guys to take the mantle. But the aftermath was still a disaster and afterwards, the Sokovia Accords needed to be placed to register all "superhumans". Let's just say not all of you were on the same side. Can't say that the discord between everyone caused Thanos to take over. Thanos caused Thanos to take over.
In my world, Ultron tried to take over the body of Vision but he failed thanks to you all and Vision basically was... Vision. One of your fellow Avengers who carried one of the stones.
You tried hard to stop him, I was away on a mission otherwise, I would have showed up to help but I always kept tabs. Thanos managed to get the last stone by killing off Vision and decided the best way to sustain everyone in the universe was to cut the population of every living being in half.
Personally, I thought he could have just snapped to make MORE PRODUCE but the man was on a power trip. I was one of the people who he snapped away. I imagine you being you, would have known this already.