Prior to its acquisition by Disney, 20th Century Studios, formerly known as 20th Century Fox, had a deal with WarnerMedia which meant that all of the former's theatrical releases would go to the latter's streaming service, HBO Max. WarnerMedia held the first-run TV and streaming rights. This deal was set to stand until the end of 2022, however, Disney and WarnerMedia have now altered the agreement.
Disney, with their own streaming services (Disney+ and Hulu), naturally want a cut of the 20th Century Studios releases. Thus, HBO Max and Disney's streaming services will now share the releases between them. That is to say, 20th Century Studios' theatrical releases will now appear on both HBO Max as well as Disney+ or Hulu, one of the latter at a time.
According to Variety, his new arrangement will last for at least the next year and begin with the release of the upcoming animated movie Ron's Gone Wrong which debuted in theaters back in October. Said animated movie will now arrive on Disney+ rather than Hulu on December 25th and simulateously become available one WarnerMedia's streaming service, HBO Max.
Following the agreement's conclusion at the end of 2022, it's believed that the theatrical releases of 20th Century Studios will be exclusively available to stream on Disney+ and Hulu.