Not too long ago, Photobucket decided to abruptly end the ability to hotlink their images unless you paid them $400 per year. (https://www.theverge.com/2017/7/4/15919224/photobucket-broken-images-amazon-ebay-etsy-paid-update) Which, uh... kind of sucks, but whatever.
So anyway. If you have Photobucket links in your sig or in your settings, they will no longer work, so I suggest going through and removing them or pointing to images hosted somewhere else. (Or you could pay them the $400 but there is seriously better hosting at 10% the price so don't do that...)
At some point relatively soon, I'll edit it myself for people who haven't updated their stuff yet, but I'll just delete the links-- so if you'd rather keep things looking nice, you probably want to do it yourself.