Remove fcitx5:
sudo pacman -R fcitx5
or
pamac remove fcitx5
Then reboot.
fcitx5 was likely installed as a build dependency of sdl2, which was moved to the AUR and replaced by sdl2-compat. Users who update using Pamac and have the AUR enabled seem to be the only ones who have experienced this issue. It looks like a bug in Pamac drew in the dependencies required to build the AUR version of sdl2, even though sdl2 was going to be uninstalled.