I met Brianna briefly at a gathering in the mid-late 2010s (I knew barely anything about her at the time) and she passed to me. Hence why I also tend to reflexively use female pronouns out of habit. I just had no reason to think Brianna was trans, mostly because MtF crossdressers just did not take up any space in my headspace at the time. Brianna is very tall, but doesn't have broad shoulders or a very "male" build, so I took her as a tall woman and did not give it another thought.
Am I a retard? Yes, but lots of normies are retards, so there's a good chance Brianna actually fooled a lot of people out there.
Edit: it wouldn't be surprising if a lot of people clock Brianna a lot more now than they did even five years ago, not just because of twink death, but because once you get some level of awareness of troons you can't help but clock even the "passing" ones.
FtMs complain about this a lot as well: the clocking ability of the general public has steadily increased in proportion to all the tranny propaganda and "days of visibility" and now even very butch FtMs don't pass like they used to. It's probably part of why Brianna is so angry at other trannies.