Variety:

Sony Pictures Entertainment and The Walt Disney Studios jointly announced that Marvel Studios and its President Kevin Feige will produce the third film in the “Spider-Man: Homecoming" series, starring Tom Holland. The film is scheduled for release on July 16, 2021. As part of the arrangement, Spider-Man will also appear in a future Marvel Studios film. Amy Pascal will also produce through Pascal Pictures, as she has on the first two Holland-led films.

No word on the financial side of this, but I had a hunch that the earlier back and forth was about leverage at the bargaining table…for both sides.