NASA's comment on this: "Seen nearly edgewise, the turbulent disk of gas churning around a black hole takes on a crazy double-humped appearance. The black hole's extreme gravity alters the paths of light coming from different parts of the disk, producing the warped image. The black hole's extreme gravitational field redirects and distorts light coming from different parts of the disk, but exactly what we see depends on our viewing angle. The greatest distortion occurs when viewing the system nearly edgewise."
The gif imitates the appearance of a black hole in which the incident substance has gathered in a thin and hot structure - an accretion disk. It is clarified that the extreme gravity of a black hole distorts the light that comes from the accretion disk, which distorts its appearance.
When viewed from the side, the disk on the left looks brighter than on the right, the researchers write. On the left side, the luminous gas moves in our direction, which adds brightness to it, and on the right side, the gas moving away from us seems duller. If you observe the disc from the front side, this asymmetry disappears.