Lets focus on a clear 1080p 60FPS stream. Do all of these:
1. Your GPU is maxed out and OBS can't render scenes and encode frame fast enough. Running a game without vertical sync or a frame rate limiter will frequently cause performance issues with OBS because your GPU will be maxed out. OBS requires a little GPU to render your scene.
Enable V/G-sync or set a reasonable frame rate limit (60, 30) that your GPU can handle without hitting 100% usage. Find the settings where your games will consistently run at
> 90FPS and then cap at 60/enable v/g-sync with monitor at 60 Hz.
If that's not enough you may also need to turn down some of the video quality options in the game.
2. Run OBS as Admin
3. Create a new scene collection with 1 scene with 1 game source
4. Google/YouTube (premier sponsor of OBS)
recommends 35 Mbps for 4K 60FPS and you're using 16 Mbps. That's 46% of the recommendation. You either need to increase your bitrate or lower your output resolution/framerate. I would go with lowering your output resolution to match the game/screen resolution. Your card also supports H265/HEVC which gets better quality per bit. YouTube supports that.
5. Your log contains streaming sessions with dropped frames. This can only be caused by a failure in your internet connection or your networking hardware. It is not caused by OBS but OBS can help. Settings > Advanced > Network and Enable Dynamic Bitrate. You also need to configure your streaming settings to use the RTMP instead of RTMPS server.
If still having issues, post a new log.