【Update 2, 2021.7】 DDG contacted customer service and got confirmation that “previous” here does in fact refer to previous versions of the regular Platinum card, not other types of Platinum cards.
‘previous’ means previous versions of the same Platinum Card. The co-branded Platinum cards are considered different products. So if you aren’t flagged for other criteria (e.g. gaming behavior) , you would still be eligible for the welcome bonus.”
【Update, 2021.7】 According to a data point in a comment on DOC, someone had already received the bonus on the regular Platinum card and, after the terms changed, applied for the Schwab Platinum and successfully received the bonus. It looks like this newly added language only restricts the same version of the Platinum card.
The AMEX Platinum family underwent major changes today: the annual fee increased, and several new benefits were added. In the application terms for the Platinum card, this sentence now appears:
Welcome offer not available to applicants who have or have had this Card or previous versions of the Platinum Card. We may also consider the number of American Express Cards you have opened and closed as well as other factors in making a decision on your welcome offer eligibility.
Some people interpret this to mean that if you previously received a bonus on the Platinum card, or on another type of Platinum card (such as Schwab, Morgan, etc.), you would not be able to get the welcome bonus on this new Platinum card. Personally, I think that if AMEX really wanted to prohibit that, it should do what Citi ThankYou cards and Chase Marriott cards do: explicitly list the conflicting card names. The phrase “previous versions” is just too vague.
Maybe AMEX is only blocking people who previously had the original Platinum from getting a new original Platinum bonus, and people who previously had Schwab from getting a new Schwab bonus. In practice, how AMEX enforces this can only be determined by whether applicants are actually able to receive the bonus. My guess is that the welcome offers on these cards will probably stay unchanged for now, so it may be best to wait for more real data points.
For reference:
Restriction on Citi ThankYou cards:
Bonus ThankYou® Points are not available if you received a new cardmember bonus for Citi Rewards+®, Citi ThankYou® Preferred, Citi ThankYou® Premier/Citi Premier® or Citi Prestige®, or if you have closed any of these accounts, in the past 24 months.
Restriction on Marriott cards:
Eligibility for this product: The product is not available to either: (1) current cardmembers of the Marriott Bonvoy™ Premier credit card (also known as Marriott Rewards® Premier) , Marriott Bonvoy Boundless™ credit card (also known as Marriott Rewards® Premier Plus) , Marriott Bonvoy Bold™ credit card, or(2) previous cardmembers of the Marriott Bonvoy™ Premier credit card (also known as Marriott Rewards® Premier) , Marriott Bonvoy Boundless™ credit card (also known as Marriott Rewards® Premier Plus) , or Marriott Bonvoy Bold™ credit card, who received a new cardmember bonus within the last 24 months.