While you see certificate error, you should press "Show Certificate" and then "Always trust when connecting to "your_remote_pc"
Then you won't see certificate error prompt again.
To Developers of Microsoft Remote Desktop for MacOS:
Please stop annoying users with prompt 'The certificate couldn't be verified back to a root certificate. Your connection may not be secure. Do you want to continue?'
IIRC, the issue isn't reproducible with the Remote Desktop Connection client for Windows, as this has a feature that saves the user preference to not keep checking that exact certificate, or, alternatively, never check certificate authenticity.
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Hope this helps,
Carlos Solís Salazar
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