How do I get good quality on my youtube videos?

[Kusu]

Hey everyone.

My general question is how to get such a good quality after uploading to youtube like this video for example:

- YouTube

Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube.

www.youtube.com

Is it because he uploads in 4K and gets the VP09 codec? I have tried so many times and my Videos are still with 4K so pixelated after upload even with the VP09 codec. Here is a test video for example.

- YouTube

Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube.

www.youtube.com

Or is it because of the new NVENC encoder? Because I have an AMD GPU (RX 6800 XT) and an AMD CPU (Ryzen 5800X).
My source video looks so good and smooth but when I upload it even with the VP09 codec (upscaling from 1920x1080 to 2K or sometimes to 4K) it just looks so ugly.
I will leave my OBS settings here for you.