It'd be obvious that
texlive-core has been replaced with
texlive-basic but consequence is the font needed,
lmodern.sty, has gone too
$ sudo pacman -S texlive-core
resolving dependencies...
looking for conflicting packages...
:: texlive-core and texlive-basic are in conflict. Remove texlive-basic? [y/N]
error: unresolvable package conflicts detected
error: failed to prepare transaction (conflicting dependencies)
:: texlive-core and texlive-basic are in conflict
How can then latex be installed complete with basic, common fonts (or style) performing as good as it was, regardless which one of the two latex packages is to be installed ?
I think you might be looking for texlive-fontsrecommended package.
Also I suggest the man page for pacman -F;
user@host ~ $ pacman -F lmodern.sty
world/texlive-core 2023.66594-7 (texlive)
usr/share/texmf-dist/tex/latex/lm/lmodern.sty
world/texlive-fontsrecommended 2023.66594-19 (texlive) [installed]
usr/share/texmf-dist/tex/latex/lm/lmodern.sty
extra/texlive-fontsrecommended 2023.66594-19 (texlive) [installed]
usr/share/texmf-dist/tex/latex/lm/lmodern.sty