Uremic pericarditis, which causes fibrinous pericarditis, presents as a yellow heart with hair-like stuff. The sources are pathology books (check Google Books) and autopsy photos (some are on Google Images, kind of NSFW). It used to be associated with "heroic death". Then "Coração Peludo" got several meanings, so I can imagine someone familiar with those and looking for references of "yellow heart", might've found examples of "hairy heart" and drawn just that.

I'm guessing they tasked a single person with adding the emojis (how hard is it to draw some simple colored shapes, right?), and didn't have anyone review them. They probably were also told not to look at examples from competitors, in case they copied them too closely and got sued for copyright infringement.

As for Unicode... it's a shame person figures can be made of "group type {shape [+ skin tone] [+ gender] [+ hair color]}*n", but they didn't use general color modifiers for the basic shapes. 🐈‍⬛