It landed in the spam folder.
It happened to me already, in 2012. I filled in a form at a conference to some Google recruiter, and the follow up email they sent ended up in my spam folder.
Is it common?
For work I need to deal with gmail marking some messages from my mail server as spam, and it's not fun. I wonder how much of a priority it is for them to improve on this.
Some examples of spam from Google:
Years ago I unsubscribed to emails from YouTube, but they just kept coming. I kept hitting that SPAM button.
I get a lot of pointless informational emails from Google that I can't unsubscribe from. I hit SPAM on all of them.
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The point to remember is that there's no magic rule to follow that makes bulk / automated email "not spam." If enough people think it's SPAM, the filters will learn to filter it out.