If you get this despite running just yarn without passing in the said argument:
Your lockfile needs to be updated, but yarn was run with
--frozen-lockfile.
Make sure there is not a .yarnrc with --install.frozen-lockfile true in any of the
parent directories. I had one where I didn't expect it, so it didn't occur to me to
look and I've wasted a good amount of time on it. Just check it - just in case.