The effect shown in the gif is called gravitational lensing.
What is gravitational lensing?
Gravitational lensing is the effect seen when an object behind a massive object is in the line of sight with the earth. For example:
Earth ————>Massive Object—————->Far away object
When we try looking at the far away object, the massive object bends space-time around it, causing the light rays from the far away object to travel in a curved path around into our line of sight.
As a result of this, we can often see the far away object magnified which helps astronomers understand the early universe. The gif shows a far away galaxy being gravitationally lensed by a closer black hole.