Most Fediverse software supports image uploads, so there’s no reason to use Imgur for image hosting. Hell, even on my small single-user server (atomicpoet.org), image hosting is easy peasy. Not only is Imgur not needed, they’re an annoyance for those of us who are used to seeing images natively on the Fediverse.
I know habits are hard to break, but just remember: this isn’t Reddit 🙂
I suppose if you wanted to be really certain your uploaded images would remain under your control, you could post them to a PixelFed instance and point it to your own domain like images.mydomain.com. That way you could always redirect them if your PixelFed instance goes down.