Why does pacman -Syu remove packages installed with yay?

Using AUR can be troublesome on Manjaro stable branch - as anything between 2 and 6 weeks may may pass before packages synced from Arch reaches Manjaro stable.

As you present yourself as 10y Gentoo user I dare say - switch to unstable branch and make your life easier. And remember a full system sync too. You will appreciate the change.

sudo pacman-mirrors -aS unstable && sudo pacman -Syyu

For informational and educational use