This is a minor culling and I can’t prove that Logitech is acting maliciously, but the effect amounts to the same.
A while back I subscribed (via my Gmail account) to a Logitech newsletter because I realized I buy a lot of Logitech mice (and keyboards, to a lesser extent). For some reason, these messages aren’t getting forwarded to my current email, despite Google not marking them as spam. Odd.
But I then decided I don’t really want to get these anymore, anyway, so I hit the ol’ Unsubscribe link at the bottom of the most recent newsletter.
It took me here:

Yes, “unsubscription error.” Whoopsie, we didn’t unsubscribe you, our bad! Try again or go through our customer support hell, and good luck with that lol!
I tried a few more times, the error persisted. I then did the following in Gmail:

Problem solved (for me)!
(My current mouse is still Logitech but my keyboards are from Keychron and Drop.)