It's believed that Square Enix previously signed a multi-year deal with Marvel Studios to support and develop new content for Marvel's Avengers until either the deal expires or it's renewed. More than two years after the game came out in the midst of the COVID-19 pandemic, the said deal may soon run its course.
According to eXputer, Marvel's Avengers is off to the "sunset" next year as Crystal Dynamics will have no more content planned for 2024 and the game's lead designer, Brian Waggoner, will leave by then. The report explains that Crystal Dynamics' support for Marvel's Avengers was only going to last for only 3-5 years. It's unclear if this has something to do with a new management taking over or if this is just because the deal with Marvel Studios has expired.
Marvel's Avengers was the first modern AAA project featuring titular heroes. It wasn't afraid to ride the popularity of its Marvel Cinematic Universe counterpart ahead of its launch. But, the goodwill fostered by the MCU post-Endgame wasn't enough to save it. The issue-filled launch, confusing game design, and forced live-service mechanic, among others, all combined to make it a rather mediocre outing.