Blurry forward shaded anti aliasing in UE5

I’m using forward shading to get crisp MSAA, and for some reason, when I upgraded my project from 4.27 to 5.0, everything went really blurry:


I noticed that the “screen percentage” setting in the editor viewport was set to 66 for some weird reason, and changing it to 100 makes it crisp again, but NOT when you hit play:

Why is UE5 doing this and how can I get it crisp?