Just off the Mardi Gras last week. Yes the party changed, There was one and they severed / handed you a glass of wine on your way in or soda if you wished. No more mixed drinks at the "party" but you did receive a free drink voucher posted to your sail and sign account to get a free drink at any bar. From 1 hour before the party until cruise ending. I am not Diamond so do not have any info on a $50.00 credit unless this is being confused with the $25.00 credit P/D where receiving for booking a sailing during covid-19. So yes the party happened on the Mardi Gras.