But to be clear. All they get at most is your IP address. That's not worth much alone.
There is a setting that prevents sending the IP address by caching the image. lemmy.world should definitely enable that. They don't do that right now, unfortunately.
When the image of "Nicole" is loaded, your computer/phone connects to another server and transfers your IP address. But it currently looks like it's not that big of a problem. Still a fix will be implemented soon to prevent this.
In the fediverse you are allowed to post thinks like these ✊