Blurry stream and recording, no fixes worked so far

[monorpheus]

Hi all. I'm new to all of this and don't really understand what I'm looking at when it comes to the settings of OBS. I have done multiple test streams (using the bandwidth test thing) and some recordings, and all of them are blurry, especially when I move. It's just the game having the issue, not any of my overlays. I've spent a good hour plus looking at threads, changing settings on both my game and my OBS, to no avail at all. My bitrate is 6000, my resolution is 1920x1080 for my canvas and output, the game resolution is also 1920x1080. Someone online said to put the key frame interval to 2 so I did and there's no difference. I had the game capture source set to fit to my screen at first, then I turned that off and thought 'if this helps, I'll just make a small overlay to cover the black bar at the bottom' but it's made no difference anyway.
I'm kind of stuck now. My PC is getting old now so I would understand if it was always like that, but the game looks fine on my screen, it's just the recording that's blurry.
Edit just to add: I changed the colour format to I444 but the difference was miniscule. I also tried a screen capture, rather than game capture. No difference. Interestingly, the stuff on the screen if fine when you see OBS, but when I go onto Minecraft, it blurs

 

[R1CH]

This is expected during high motion at only 6 mbps.

 

[Sparkwing]

As R1CH said, this is normal for low bitrates. 6 Mbps is really only enough to make 1080p 60 FPS video look okay.

Based on the bitrate limit, it sounds like you're streaming to Twitch. This means you're locked out of using the newer video codecs that could improve quality a bit. The easiest and common solution is to drop your streaming resolution from 1080p. With less data to be compressed, the video won't look as blurry in motion.

Lastly changing the color format to I444 would make quality a little worse since the video will now be compressed more to account for the increase in color data.