This is because I finally took my PowerShell-based LinkPoster and stuck it into an online automation system. In this case Microsoft's Azure Functions. Which runs this bit of PowerShell once per day at midday, causing it to post the links.
If you are the kind of person who enjoys playing around with "serverless" computing, link posting, etc. and want to have a go with it all of the code, and instructions for getting it running is on GitHub here. You'd almost certainly need to be comfortable with a bunch of software dev stuff to get it up and running, but I've hopefully made it as easy as possible if you are that kind of person.
Original post on Dreamwidth - there are comments there.