woah, rimu answered in under 20 minutes, they said:

I found the cause - recent garfield posts have the 🔗 character in their body, which I added to our spam filter some time ago. I’ve removed it now so future posts will come through ok.

https://piefed.social/post/1463125

dang, that’s like, inspirational, I oughta aspire to be that good at something!