Welcome to the forum! 
It appears you may not be up to date, please see Pacman-mirrors - Manjaro. Update your AUR packages after you have confirmed your repo packages are fully up to date.
FYI, TeX Live packages have been reorganized recently detailed in a recent Stable Updates post.
pdflatex is part of texlive-bin:
❯ pacman -F pdflatex
extra/texlive-bin 2023.66984-15
usr/bin/pdflatex
It does not appear perl-latexml has ever been in the repos as it’s been in the AUR (Arch User Repository) since 2015.