Problem with expl3.sty

[Karl Berry]

    This error usually happens because TeX Live sometimes creates local
    format files when updating, and "forgets" to regenerate them 
    ...
    https://tex.stackexchange.com/a/598609/134574

As far as I can think of, install-tl/tlmgr never creates "local" format
files, despite the statements in that tex.sx post. Users have to
knowingly create them themselves by running fmtutil-user. Am I wrong?
Anyway, it would be wrong for tlmgr to update them. The advice in that
post to remove them is usually what is desired. --best, karl.