According to physicists, black holes are the most chaotic system in our universe.
In Ray Bradbury's legendary story "And Thunder Rocked," one butterfly crushed in the distant past led to catastrophic changes in the future. Largely due to this story, the term "butterfly effect", coined by Konrad Lorenz, became popular - when a minimal impact on a system causes an avalanche-like catastrophic change.
Physicists Douglas Stanford and Stephen Schenker believe that falling of any elementary particle into a black hole is a typical example of such an effect. The fact is that the so-called Hawking radiation is generated at the edges of the black hole, which is given by individual elementary particles that have managed to escape from the cosmic mouth. But each addition of mass changes the size of the black hole, and the Hawking radiation remains beyond the event horizon - that is, where no particle is able to escape.
Thus, any electron falling into a black hole changes the situation in it so much that it is simply impossible to predict these changes. This leads physicists to the conclusion that there is continuous and endless chaos inside these mysterious objects. We do not know if such a description helped you better understand what is happening behind the event horizon of a black hole, but the scientists themselves are confident that their work will help to understand the discrepancy between different physical theories and formulate a theory of quantum gravity.