In the harsher lighting, you can just barely make out the difference in makeup:
So, how did Gaga cover up her ink? She enlisted professional makeup artist Mike Mekash, who works on American Horror Story as well as on movies like Mad Max: Fury Road.
Mekash revealed that he used PAX (an acrylic adhesive based makeup) and skin illustrators to complete the job, and he said on Facebook, "The covers I did looked great on the red carpet and on stage when she WON! And for 99% of the press photos." As for the why? You'd have to ask Gaga.
Plus, Leonardo DiCaprio exclusively explained to ET his hilarious reaction to Gaga's win at the Golden Globes: