Oh, and the instance actually does return an error page saying "This instance is under maintenance.", so it's remotely possible that this Friendica message is based on misinformation, and that the instance being "down" may be only temporary? (I have no idea)

For some reason Piefed is removing the title of the post, which links to a Reddit thread as a source. That thread clarifies: "I emailed the address given on the page and was told the instance service was cancelled by the instance owner and it's unknown whether there was a plan to migrate or just shut down completely".

Looking at the under maintenance page myself, the email seems to be the server host's, so this isn't the instance owner being unsure about their future plans yet, it means the hosting relationship is cancelled and the host doesn't know about things beyond that.