what is your bitrate set to? for 1080p 6k bitrate is good (and the highest twitch accepts for example) and 4k for 720p. you should post pics of your settings so we can look at them

Here's a chart I rely on for determining a good bitrate

Keeping in mind, the game is also an important factor. Slow-paced puzzle games with minimalistic graphics can get away with a far lower bitrate to get good quality than a fast-paced game with lots of particle effects or something.

I find this chart tends to favor the best case scenario, so if your content has a lot of fast-moving stuff on screen I suggest increasing the bitrate by like 25%