Developer is targeting individuals with a blacklist he maintians, enabled by default. Dev can do what he wants, but I’d like my home instance to consider removing it as a front end.
YSK post: https://lemmy.world/post/49813386
Dev post about it: https://lemmy.today/post/57096701
Blacklist: https://copyparty.adrian.place/u/?doc=policy.json

This page might help, it explains what alternative UIs are and which ones are available. Some of them can also be used in the mobile web browser.
https://fedecan.ca/en/guide/threadiverse/alternative-uis
(It says tesseract is available on lemmy.ca, but that is out of date now)
This issue with Tesseract affects anyone that was using it. So it is possible that someone did not see a comment or post you made, without knowing why they could not see it. Past that, it likely hasn’t affected you since you said you don’t use it :)
It sounds like I might not have known if I was using it or not, depending on how I accessed Lemmy.
It’s extremely unlikely that you were using it without knowing. Though if you were you’d know now because reloading the page would load Lemmy-UI instead of Tesseract. They don’t look at all alike.
edit:
https://photon.lemmy.ca/ looks very similar to tesseract, if you want to see the difference.
Thanks so much for sharing this, I couldn’t find an actual screenshot of Tesseract anywhere what with Dubvee redirecting everything to a “goaway” picture.