Many may not remember it, but there was a time when Marvel was at risk of disappearing, so as a desperate measure they decided to sell the film rights of their characters to various studios. With this, for example, the X-Men belonged to Fox or Spider-Man to Sony.
Then Disney arrived and everything changed, as it ended up buying Marvel, created the MCU (Marvel Cinematic Universe), bought Fox and made an alliance with Sony so that Spider-Man, one of the most important characters of Marvel, was part of the MCU. In other words, everything seemed to be in order again.
In 2015, Disney and Sony signed a major agreement that made Spider-Man appear in three movies by Disney-owned Marvel Studios, while some Marvel characters would do the same within arachnid movies. The terms of all this benefited Sony, as it held the rights over the character, was responsible for the financing, as well as the profits, distribution and "final creative control" over the superhero.
Obviously Disney wasn't going to stand idly by, and more so now that it has all its characters back after the Fox purchase, so, according to Deadline, they sat down again with Sony to renegotiate the agreements related to the use of Spider-Man. And according to the information, this did not end well, as both companies would have decided to break the current agreement, which means that Peter Parker would be out of MCU.