Term for video artifact of blocky grey visuals

What is the name used for the artifact in digital video in which gray (or sometimes purple) blocky "smears" appear on the screen?

Here are three example images: https://imgur.com/a/oZkQwm4

Solution 1:

I would call the 3 images respectively (i) somewhat pixelated or with a few pixelations, (ii) pixelated, and (iii) heavily pixelated.

OED:

Pixelate 1 b. intransitive. Of an image: to break up into a number of discrete pixels.

1994 N.Y. Times 7 Aug. ii. 1/2 So finely rendered is the detailed landscape that the image ‘dithered’ or began to ‘pixelate’ into a gridlike pattern not unlike what one would expect if a snapshot had been taken through a screen door.

2. transitive. To blur (parts of a televisual or photographic image) by converting into a number of fairly large, indistinct, pixel-like patches, for purposes of censorship or to maintain the anonymity of the subject.

2003 Church Times 28 May 12/3 Of all the British papers, only The Independent pixelated the faces of all prisoners of war, whichever side they came from.