I moved the monitor and suddenly my whole setup felt wrong

Cleaned the desk, moved the monitor back a little, and spent the next session convinced I had changed a mouse setting. I had not. Everything just looked slightly different and I was overcorrecting.

Put the monitor back near its old position and felt normal again. Not claiming some universal magic distance. Mostly sharing because I nearly changed every setting I own to solve a furniture problem.

What is the smallest physical change that has thrown you off?