They installed a root certificate on windows computers that could have been used to MITM all traffic.
I personally had issues with the project years before that when I tried to install their Linux .deb and they ran `pip install` as root in the pre install script inside the .deb. That caused so much havoc to clean up I was pissed at them for years. Now that idiocy is blocked by default in current versions of pip.
https://github.com/rustdesk/rustdesk