0xxon
It's the official status of green card holders.
Stuff like this is quite common; we published a paper on this recently if you are interested in details: https://arxiv.org/abs/2009.08772
Depending on the day my guess was that 40-70% of people were wearing masks - more on public transit.
I assume that you mostly were at the Airport or public transit/other huge venues - otherwise I cannot really explain our different experiences.
The extension is sent unencrypted, even when using TLS 1.3. So everyone sniffing the traffic can tell where you are surfing to, even without DNS.
It gives you very deep visibility in the supported protocols, dumps easy to parse log-files by default (see e.g. https://www.bro.org/sphinx-git/httpmonitor/index.html for HTTP information) - and it is fully scriptable.
(Disclaimer: I am involved with the project.)
(It is actually not emscripten -- it uses a z-machine emulator I adapted to js a long time ago to run the z-machine version of star trek. But - should be good enough :) )