Source: https://twitter.com/monsterhunter/status/1729672458775519663
Edit: From @[email protected] '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.
Although it still sucks it’s being removed, these DLCs were all free event quests and did not cost extra.