Two days later my product completely vanished from the Google rankings. No cause that I could think of; I wasn't doing any questionable SEO or other manipulation at the time. I later found out there were Google people at the conference, though I don't know whether they were at the talk or not.
Correlation != causation so I'm hesitant to definitively call shenanigans on this. But it does make me believe ProtonMail's story a little more.