Well, #IFTTT continues to make its free tier even more useless.
They've decided to make their webhooks service (previously known as the Maker channel) only available on a Pro account.
So, in addition to only being able to use three recipes total, webhooks aren't even one of them.
I guess it's time for me to get webhooks working on my n8n installation, and completely delete my IFTTT account.
It used to be such a good service, and a nice alternative to Zapier for those who couldn't afford it. Now, it's still not as good as Zapier, and there's no point using it if you can't pay for it.