I had the same problem on WSL2. I also have an https_proxy environment variable set to my company's https_proxy server.
When working inside the company VPN, this did not work since (I believe) WSL2 have a problem using the proxy settings correctly.
Outside the company VPN, un-setting this environment variable, fixed the problem.
so (outside the VPN):
unset https_proxy
and then
nvm ls-remote --lts
worked.