Another diagnostic would be to use
julia ---startup-file=no and rerun versioninfo(). That will completely rule out any contribution of startup.jl.
Also check your shell startup files such as .profile, .bashrc.
Edit:
In this case the issue ended up being due to a rogue VSCode-Julia extension setting. To resolve, clear the “Package Server” setting for the Julia extension within VSCode.
See here for more details:
Having an incorrect JULIA_PKG_SERVER will make it challenging to get new packages.