Up front disclaimer: this is my own personal conspiracy theory with no objective proof. I have quite a few pieces of anecdotal evidence to support this, but anecdotal is anecdotal.
Looking through the comments, everyone is talking about Amazon.com purchases, but the much quieter, arguably more valuable move on Amazon's part would be to do this via AWS. If you're running your entire system on AWS, Amazon immediately knows what kind of scale you're currently running. Depending on the type of product, they can pretty easily ballpark what your profit margin is based on your pricing model and all the metrics they have on your application (which is basically everything).
The application of this data could be used for acquisition targets, deciding which products to build into AWS, ongoing competitive analysis when they do build those competing products...
I saw the drop and wondered if there was something afoot, then talked myself off that ledge and assumed this was probably some kind of normal flag like ring detection triggered, etc.
Interesting additional note, though, the title has (relatively recently) changed to "Superhuman embeds tracking pixels in user emails" versus the actual article title of "Superhuman is Spying on You"
Looking through the comments, everyone is talking about Amazon.com purchases, but the much quieter, arguably more valuable move on Amazon's part would be to do this via AWS. If you're running your entire system on AWS, Amazon immediately knows what kind of scale you're currently running. Depending on the type of product, they can pretty easily ballpark what your profit margin is based on your pricing model and all the metrics they have on your application (which is basically everything).
The application of this data could be used for acquisition targets, deciding which products to build into AWS, ongoing competitive analysis when they do build those competing products...