I was just checking my profile earlier when I saw this:
Is this a new level? Or is it just a way of telling me that I've gotten to max level?
EDIT: You'll have to open the image in a new tab, it doesn't want to show for some reason.
It looks like that's a feature of the new version of the site. On the old site, it gave a figure for the number of XP needed to get to the next level, even though it wasn't possible to get there. It looks like that's been improved in the new code - since there's no level after 25, "infinity XP" is accurate.
I don't need to see your picture to recognise this: this has existed in the new redesign. I think Duolingo's motive to do this is a couple of people over the years have been coming to the Duo forums asking whether they can go past level 25, and instead of nowhere apart from the unofficial Wikia, people can just find out the answer easily by looking on their profile.
You've linked to the Imgur site about the image, not to the image itself. If you edit your post and add ".jpg" to the end, it'll work.
I haven't been keeping my streak as well as I should really xD. I used to have a 140+ day, but I lost that and haven't really been bothered since. P.S. he*