Be careful, additional software potentially malware.

https://github.com/null-dev/firefox-profile-switcher-connector/issues/7

https://github.com/null-dev/firefox-profile-switcher/issues/17

Both are open-source, so you are free to check by yourself. I'm not too great at Rust, so I can't confirm anything, but it's always good to be wary.

I'd recommend just using firefox.exe -P for now until the issues are addressed. It's a lot uglier, but it does its job