Technology

This is possible because Lemmy doesn't proxy external images but instead loads them directly. While not all that bad, this could be used for Spy pixels by nefarious posters and commenters.

Note, that the only thing that I willingly log is the "hit count" visible in the image, and I have no intention to misuse the data.

I guess it knows that it's unknown

This is true for most link aggregators that attempt to render external content. Proxying images and videos would dramatically increase costs.

If you care that much about anonymity, use a VPN/Tor and a browser with advanced fingerprinting resistance — tor browser, mullvad browser, or firefox with resist fingerprinting = true.

My favorite Linux distro: Windows.

This reminds me of those old forum signatures which looked like a signpost, and showed your IP address, browser, OS etc. They were pretty popular back then (when no one cared about their privacy), to the point that some folks even made parody versions of those signatures (like changing the IP to "127.0.0.1" or writing a funny message).

But I'm not on chrome mobile...

*brave