I have a 800+ streak, so my icon used to always be orange. It didn't even change when it "got sick" for everyone last year. Now they seem to have removed that feature and it "gets angry" if it's past 22.00 and I haven't done an exercise yet. Which is what I very often do.
Disable automatic updates in the play store. I have them dissbled for all my apps to have better control over what is pushed upon me. I noticed that also stops the Duo icon to change when I was slacking off.
Nice work. I also share this gripe, it seems the people at Duolingo are biased in thinking that getting started early is better, which is not true at all. I wish they removed the angry icons and replaced them with ones that weren't so biased.
Like this, but with the kinky green owl:
*I think there is a setting in the app that turns off changing icons entirely. Can't find it rn tho...