There are reports (1,2) that American Express can now see across accounts if you have multiple logins. Reddit user Slytherin23 first reported that they no longer see Amex gold upgrade offers since the gold card login knows the user has a Platinum on another login.
Reddit user parts_unknown- then confirmed that this was true, even if the MR accounts are separate. Their P2 shows “add an AU offer” for their Business Platinum card when they are browsing cards on their next login with a different membership rewards account.
