I also have the same "too many bank cards" rejection reason. Here are my cards over the past 2 years:
(the dates to the right indicate when that card will fall off of 5/24 count status)
Cards:
Barclays AAdvantage Aviator Red World Elite MasterCard (03-01-2020)
Chase Freedom (08-01-2020)
US Bank Altitude Reserve (08-01-2020)
Sears Mastercard (09-01-2020)
Barclays Arrival Plus World Elite MasterCard (01-01-2021)
American Express Marriott Bonvoy (03-01-2021)
Rakuten Cash Back Visa (formerly Ebates) (09-01-2021)
I'm guessing this is too many?