So here's the fine print on the 20k Chase portal offer, bolding mine:
Up to 20,000 Bonus Points Through Chase Travel: With this bonus offer, eligible cardmembers who have not purchased travel through Ultimate Rewards/Chase Travel since 08/15/22 and who activate this offer can then earn either 20,000 bonus points when they purchase a hotel stay through Chase Travel totaling at least $500 or 10,000 bonus points when they purchase flights, car rentals, cruises, activities, or tours through Chase Travel totaling at least $500 in a single transaction. Purchases must be made by 01/31/25 11:59 PM ET with the same eligible card used to activate and travel must be completed by 08/31/25 11:59 PM ET. Bookings can include point redemptions, however, point redemption values will not count towards offer minimum spend. Only purchases completed through Chase Travel are eligible, “reserve now, pay later” and cancelled or refunded purchases are not eligible. Please allow up to 8 weeks after completing your travel for bonus points to post to your account. This bonus offer is non-transferable and applies only to cardmembers who receive marketing communications for this offer. Account must be open and not in default at the time of fulfillment. Eligible credit cards: Chase Freedom card, Chase Freedom Unlimited card, Chase Freedom Rise card, Chase Freedom Flex card, Chase Freedom Student card, Chase Ink Cash Card, Chase Ink Business Cash Card, Chase Ink Business Preferred Card, Chase Ink Business Unlimited Card, Chase Ink Plus Card, Chase Ink Business Premier Card, Chase Sapphire card, Chase Sapphire Preferred card, Chase Sapphire Reserve card. Please note that even though you have an eligible credit card, you may not be eligible for this offer based on your account status and other factors. This bonus can only be earned once per cardmember, regardless of how many eligible cards a cardmember has, and will be awarded to the eligible card used to activate this offer. We reserve the right to cancel or modify this offer at any time without notice. See your Rewards Program Agreement for more details about earning and redeeming points.
I'm personally going to tread lightly with this because of the "cardmember" lingo. My thought is they could have said something like "In order to be eligible for this offer, the card used to activate this offer must not have been used to purchase travel through UR/Chase Travel since 8/15/22" if that's what they meant. But they specifically say cardmember.
On the flip side, if the offer is targeted and activation is successful, you'd think that would be sufficient diligence on the part of the cardmember.