Why does my Android camera app mirror my selfies, and why again, as I already turned this off some time ago. Only noticed when there was a sign in the background. Annoying misfeature, wtf (yes, please tell me why this is a great feature for you, this might actually make me happier)

Because people who take selfies are mostly cretins who think it should work exactly like a mirror, and get incredibly confused when they hold their right hand up and don't see that result mirrored in the camera.

(It probably reverted the setting after an update. Think mine did that too.)

@AlmondSauce I'm fine with mirroring for the display while taking the picture, but it shouldn't affect the captured images.

Luckily there are countless camera apps and I'm sure this is fixed in some of them. You could also try a different rom or even fix it yourself if you bought a good phone.