I ran afoul of this about a year ago, and have since noticed others having the same issue a few times since.
Kernel.org publishes the WKD for all developers who have
kernel.org accounts, which is grand - but protonmail has a feature where it will automagically check for WKD and use it to encrypt messags.
Mailing lists & recipients without WKD will get the regular old copy of the mail.
To quote one of the other people that ran into this:
"they told me then that it's a super-pro
builtin feature that I can't disable 🤡"
That's the same answer I got & for both of us, the solution was just to leave protonmail.
Maintainers don't know about this & get "annoyed" with patch submitters & it is equally frustrating on the other side trying to figure out why your patchset has been encrypted...
The most recent occurance of this is here:
https://lore.kernel.org/all/Y6slQLto568WfmfZ@spud/I feel like it should be documented somewhere that this issue exists, process/email-clients.txt doesn't seem quite right. Perhaps the patches documenting it should be CC the users@linux.kernel.org ML?