How do I fix this? I dont understand anything.

SO yesterday I was done with my first scene and when I created a new scene this happens: Pasteboard - Uploaded Image ,
Pasteboard - Uploaded Image .
The first scene also gets this if the scene is created. But when I delete the second scene the first scene goes to normal. And I tried creating a new project but the same happened with every scene.
Please help.

It appears as if something is slowing down the drawing of the graphics or caching(not sure how to word that sorry). To move a box across a screen a PC has to basically draw it out in every position the box is in. Check and ensure that your not maxing out ram, cpu and/or gpu while Unity is open. Also if you haven’t yet try simply restarting your PC. I also have found that at times things like internet browsers can cause weird glitches like this as they tend to hang up sometimes due to ads and such.

I guess
this happened because color buffer was not cleared between frames (colors rendered previously were transferred to the next frame), also the depth buffer.

Please try changing the Main Camera component Camera>Clear Flags > Skybox