Why is my Visual Studio text editor font all bold now?

The solution that kspearrin mentioned in the comments section solved the problem for me:

I was trying to adjust the zoom level using the mouse wheel and it never went back to a true 100%. When I manually adjusted it using the dropdown at the bottom of the editor window to 100% it looks fine now.

I had the same problem because zoom value was set to 98%.

Solved when I set it to 100% manually.

_{(source: ibin.co)}