Why my scene becomes pixelated when I press play?

When I press the play buttom (only the viewport play buttom, the problem doesn’t happen with the simulate) my scene becomes pixelated. Some one can help me, please?

I’m inserting two atached images. One normal and other with the problem.

I just change the quality settings and the problem is now resolved. Thanks.

how did you changed The quality settings ??

necro much? Anyway, if you haven’t figured it out you can find the quality settings for the engine under Settings → Engine Scalability Settings