Visual Artifact in Wireframe Grid/Plane
It's a interference pattern, called Moire pattern. You get them in signal analysis and various other fields. I guess it could be considered an optical illusion.

EDIT:

To elaborate, this occurs when a periodic waveform goes out of phase with the observer. In your case the periodic waveform are the lines when observed as a scanline (from left to right of the image or vice versa), and the observer is the image with a set number of horizontal pixels. In some parts, the pixel rasterization falls on pixel boundaries and then there is a watershed moment... should it be rasterized in pixel x, or x + 1. This then manifests as the wave pattern (due to the 'watershed' moment being slightly out of phase with the previous or next scanline i.e one scanline, pixel falls on x, the next scanline it falls on x+1). Also the display device can also have an effect. The moire in your image is much more pronounced on my computer monitor, than it is with my phone. (however this could be due to my phone’s browser scaling or applying some other filtering by default, which could help to reduce it).

Anti aliasing certainly helps, however moire can never be completely eradicated, only mitigated. Also note this can occur with rotated grids in orthographic, however perspective projection will certainly amplify this effect.