It's probably nothing but you should know that the "post" button on top of your homepage is hyper-linked to https://brilliant.org/avatar/change/ [just hover your mouse over it to see]. If you click on that button, you see a drop-down menu for posting notes and problems. But when you right-click on that button and try to open it in a new tab, you are redirected to the avatar change page.
This isn't that important and people are unlikely to notice this if they don't have the habit of opening everything in a new tab [or hovering their mouse over everything]. However, it does look odd and I think you should fix this.
You probably wanted the profile pictures to be hyper-linked, didn't you? Because that would make sense.
Just another harmless bug I thought you should know about.
Edit: Now it's fixed.