I think that might be because some movies are meant to be 'pivotal' movies and others are just meant to be fun stand alone romps. They can spoil some of the latter while the former has be kept under wraps. We know very little about Dr Strange 2 (other than the fact that Wanda and the Multiverse are in it), She Hulk, Moon Knight and Ms Marvel and they're all also filming. Only reason anything about Spider-Man: NWH is confirmed is because Sony is co-captioning that leaky ship and somebody leaked the trailer.
My take away is that Dr Strange, Captain Marvel and Black Panther were meant to be the Big 3 of Phase 4 and onwards. Strange gets the Multiverse, Carol gets Secret Invasion and Black Panther gets to introduce Atlantis and Namor into the MCU. Now Boseman's death has complicated their plans and thrown it all into a tail spin. They'll probably give his lines and parts to other supporting characters in order to make it work. I can see them trying to have Sam fill in the void created in the Phase 4 Trinity, I think they would have done Falcon & Winter Solider + Cap 4 anyway but like I don't think Sam was meant to be a primary 'face' of the MCU initially. There is Shang Chi but he just got here and hasn't interacted with the wider universe yet.