Do you specifically go out of your way to check who sent every transactional email you receive and take notes on which email sending service your order confirmation was sent by? That would be a very weird thing to do and would be the only way to know that.
When I receive email that is not from someone I know or understand why I receive it I check the source.
I don’t like receiving email that are not directly relevant to me.
This does mean that if it’s an order confirmation I wouldn’t check. So I may not know of legitimate emails from sendgrid only the illegitimate.
Weird? Do you know where you are? We're all nerds here, in many shades of what you label as 'weird'.