If you have the Marriott Bonvoy American Express card, you should be targetted for a new cashback offer.
You will receive £75 back when you spend £200 at selected Marriott properties in the UK and Europe by 31st December.
The offer appears to be on supplementary cards too. This would allow you to split larger bills and benefit from the cashback on both cards. I don’t know if you would automatically get the offer on new supplementary cards if you applied for one now.
Holders of other American Express cards may have a similar £50 off £200 deal which launched last month. If you got this on your Bonvoy Amex, it MAY double up with this new offer, getting you £125 off.