When will the mod be updated to version 1.21.1?
Has anyone tried updating it to the new version, if so, please share.
And why won't they update it officially?

I think everything is abandoned. I tried to install it on 1.20.1 and nothing works. I don't understand why this mod is needed at all, if you just needed to update webdisplay. Having mcef on these versions is simply useless without webdisplay or cinemamod