Most Lemmy instances do not proxy images. This means every little profile picture, every thumbnail, etc, are all downloaded from different servers. There’s very few privacy protections in clients either. It’s most likely you just scrolled past a page with a post that had that as a link.
For example, <- this isn’t actually a real image, but your client will try and download it. And you’ve just sent your IP address and browser information to it.










My problem with the own-domain tactic is that it reduces anonymity, since you’re most likely the only person using that email domain.