Source: https://twitter.com/monsterhunter/status/1729672458775519663
Edit: From @ISolox@lemmy.world 's comments below, it seems these are free DLCs which you can download as soon as you start the game. So, they aren’t removing any paid content, only free DLC.
Thanks for the info. I haven’t played MH-Rise yet, so didn’t know the details. I have updated the main post with the info that it’s free.