A different one: it’s called “Screen Sharing.app” and it’s under Utilities.

After you open it, press “Connections -> New” and start typing a contact name.

They get a little notification if they are online, and if they accept you have a seamless screen sharing experience ready to go. It’s honestly magic for the “my parents have an error message and don’t know what to do” situation.

I assume they have you in their contacts as well for it to work.