It’s weird to have that strong of a reaction. At the very least it sounds debilitating.

It's not debilitating, it just means I don't watch horror or thrillers.

It’s not even uncanny valley because Duo is not even close to human like (unless you know green bird like humans in real life, but then I’m not sure they’re human).

Okay, so that's the point. The very definition of the uncanny valley is it maps a graph. You go from something that doesn't look human at all, and then the closer you get to human, the more appealing it looks, until it looks completely human. Except when you start getting much closer and you're not quite there, there's a dip in the graph where it's suddenly horrifying before it gets better. That's the "valley". That's why clowns, marionettes, dolls, zombies, and yeah, sometimes very wrinkly old people are horrifying. Their faces are twisted, distorted, and/or malformed just enough to be horrifying. Studies show that even monkeys have the uncanny valley reaction when you distort a face in front of them. And the Duolingo owl is not just an owl-- its face takes on decidedly human expressions, which can therefore be uncanny valley. Hell, some monkeys'/apes' natural faces themselves tiptoe on uncanny valley for me as it is.

Now, some people are less sensitive/don't often see uncanny valley as much as average, while people like me are more sensitive to it. It doesn't mean the valley doesn't exist, or that I have a weird problem-- it's just that some people are more sensitive to faces. It's why autistic people are known for not making eye contact, yeah? With that said, it is not a debilitating problem. I live with it, I know which things I deal with are big problems (and there are several), and this isn't one of them.