I have been having this issue for a while now, essentially most of my objects in scene and GUI textures look like they very low quality. I have tried using a very high res image and applying the texture one of the objects, and at first glance it looks ok, but the same streaking/color-bleeding seen below shows up on the image in the solid colors. it seems to happen mostly on solid color objects…
I have set the quality in project setting to fantastic and played around with the setting as much as was intuitive… maybe I have a low resolution on cameras or in the setting which I skipped over?
in the images the lines can be seen on the grey, and in the blue, if you look closely there are horizontal changes in color.
You might check to make sure Scale (size of the game view on the screen) is 1x. Scrolling the middle mouse button while in the Game view can inadvertently change the view scale and cause everything, including the UI, to appear very low quality in low resolution.
Maybe an old topic, but if anyone still has this issue (which I did in 2020).
Make sure your RenderTexture is set to a larger height and width (the default is only 256x256).
I changed the size of the texture to full-hd (1920x1080) so I can use it on any rawimage in my game.
In my case the problem was that the game display resolution (on the top left of the Game window) was set to 16:9. Setting it to a high resolution, like 1920x1080 or 3840x2160 solved the issue for me.
