You cannot rely on this extension (or anything like it, for that matter) to replace personal research and critical thinking.

The political biases of the creators with regards to who is part of the trans community, what is or is not transphobic, what language is or is not appropriate, etc. directly impact the TOS and intended purpose of this extension, so if your politics diverge at all (which they likely will, just because of how many stances there are to have), labels on accounts and pages may mislead you.

On top of this, users can and do falsely flag accounts as trans-friendly or transphobic (I've personally been marked friendly before for simply being part of a trans-positive group which is not what the label is meant to mean, but this feature can also easily be used maliciously), and high numbers of people using the extension results in false or misleading flags having a huge impact on the amount of engagement a user gets, which homogenises what LGBT+ talking points and perspectives get seen online.

Extensions such as this can be handy at times, but without attached explanation for why a user is marked the way they are, it acts less like an informative tool and more like a prosthetic gut instinct with someone else's biases baked into it instead of your own.

I'm personally removing this extension in response to a blog that should qualify for the trans-friendly label being irreversably marked as transphobic by the creators due to political disagreement, likely on the specifics of the relationship between the intersex and transgender communities. The blog owner does a lot of really important outreach and IRL community work, and has unique and important perspectives that a lot of people will no longer engage with because of the false label.

It was nice to have quick information to look to when something didn't quite sit right with me because I have a lot of trouble trusting my own instincts, but on further meditation I'm not OK with a tool like this deciding how I should feel for me.

If you do choose to install the extension, please consider its labels an invitation to inspect further and figure out why that label is there, instead of simply taking it as an objective marker of who is or is not safe. Nobody can judge what is or is not safe for you except yourself.