I can't speak for OP but I too use per-company or per-service emails, and no they have zero connection to my main email (not even the domain actually, domains are cheap so I have multiple ones for different purposes). Since I started doing so a very long time ago I did choose a standard scheme for it (making use of the company's domain), so it would certainly be possible to recognize it's a per-company domain given human attention or (more likely) AI. Ideally the email specifically would not be something I'd see but just a pointer that would be randomly/plausibly auto-generated, and then my email server (or client) could transparently disambiguate it via a db on my side to what the service was. Then it'd be undetectable. Unfortunately while it's clear enough how all the pieces of that could come together I don't know of any existing solution and haven't had time to try to hack on it myself. So far it hasn't given me any problems however.

There was a while where I had a complex lookup system Apple got "strawberry.cake@example.com", and posting to mailing lists were sent from "steve@12.2025.example.com" - which would lose MX records after a month.

But in the end I settled on facebook@example.com, instagram@example.com, and similar obvious names.