how does hyphenation with babel-french work?

I have seen number other questions dealing with this problem but never understood how it works and how to fix it.

I installed latex with the install-tl script and selected the babel-french package.

In my document I use usepackage[french]{babel} but I get the following warning (and no hyphenation is working):

No hyphenation patterns were preloaded for
(babel) the language `French' into the format.
(babel) Please, configure your TeX system to add them and
(babel) rebuild the format. Now I will use the patterns
(babel) preloaded for language=nohyphenation instead.

I have no clue how to "configure my TeX system". When I look into /usr/local/texlive/2020/texmf-dist/tex/generic/babel-french/french.ldf I see in the header

%% This is file `french.ldf',
%% generated with the docstrip utility.
%%
%% The original source files were:
%%
%% frenchb.dtx  (with options: `french')
%% This is a generated file part of the babel-french bundle
%% to be used with the Babel system.

and then later lines dealing with hyphenation

defFB@nopatterns{%
   ifdefinedl@nohyphenation
      adddialectl@frenchl@nohyphenation
      edefbbl@nulllanguage{stringlanguage=nohyphenation}%
   else
      edefbbl@nulllanguage{stringlanguage=0}%
      adddialectl@french0
   fi
   @nopatterns{French}}
ifdefinedl@french else FB@nopatterns fi
ifdefinedl@acadian
  adddialectl@canadienl@acadian
else
  adddialectl@acadianl@french
  adddialectl@canadienl@french
fi
providehyphenmins{french}{tw@thr@@}
providehyphenmins{acadian}{tw@thr@@}

Some forums advised to run fmtutil --all but it does not solve anything and I do not understand what it’s supposed to do from the doc (man fmtutil). I have the impression that LaTeX is an aging and complex system that has a lot of border effects and is thus hard to manage without deep understanding of its behavior.