I've used Shinigami Eyes on Firefox for several years, beginning around 2020 or 2021. Since then, I've seen a notable shift in the kinds of users marked as anti-trans and trans-friendly on social platforms, most notably Tumblr.

This extension, for what it is worth, is still largely helpful when browsing online to identify public figures, media outlets, and other organizations that platform anti-trans rhetoric by marking articles, news websites, and even Wikipedia pages. This is something that this extension still does well.

However, when it comes to social platform users in queer online spaces, the kinds of users marked anti-trans have completely changed. While an official guide to who should or should not be marked red on Shinigami Eyes, this guideline no longer appears to be relevant. In the past, users were marked pretty reliably based on these rules: someone must be visibly anti-trans and/or a transmisogynist. Today, it appears that users who outwardly support transfeminine (and other trans individuals regardless of identity) are still at risk of being marked anti-trans if they speak against bioessentialism (an emphasis on someone's clinical "s*x") or speak on concerns relating to intersexism. This is strange to me, as transgender and intersex individuals face similar (NOT identical, but overlapping) issues regarding medical autonomy and civil rights.

It seems like the system of Shinigami Eyes is now primarily used to indicate that intersex and otherly-sexed individuals and activists are inherently transmisogynist. I recommend that users who use Shinigami Eyes be extra cautious in vetting who is or is not anti-trans as the extension stands today.