i've been thinking of doing this because i think life gave me a warning sign in the form of a facebook account. lol
i forgot i had created it sometime in the mid aughts and hadn't used it since then; but upon a recent login, i got an reminder about an event i planned on attending.
i purchased those tickets using my proton email address and the venmo credit card (which was also registered to my proton account) and facebook knew that i was going to that event even though i hadn't used facebook in (literally) decades and i didn't know proton was a thing when i last used the facebook account.