Security Update 2020-004: Apple Remote Desktop and Screen Sharing Not Working? Anyone else noticed?
No, we are not seeing that. Having ssh is key, you can log in and kickstart the ARD and self rescue most of the time. Even turn off remote access and turn it back on via ssh.

https://support.apple.com/en-us/HT201710

Once you get ARD or physical hands on the Mac , I would reinstall Mojave from the App Store to be sure the OS is installed if you can’t suss out what happened.