@ChristineLvX89 ,
Just for a test try changing login manager
yay -S ly
sudo systemctl disable lightdm.service
sudo systemctl enable ly.service
plymouth as a package is not used as far as I know.
Ly is a non-graphical login manager compatible with all the above mentioned DE-s.
Edit: OR
https://forum.endeavouros.com/t/guide-how-to-install-and-use-plymouth/51363