I might not be fully up to date on this sort of thing, but it looks like a policy change by Photobucket. They don't get much out of letting you host stuff and link to it on 3rd party sites, so they're trying to discourage that.
Here's an article about it:
(https://www.theverge.com/2017/7/4/15919224/photobucket-bro...). From the sounds of it you're probably going to want to find a new image host.