Is favorite a verb?
Favorite can be used as a verb to mean “to mark something online (e.g., a photo, video, or website) to visit again.” For example: “Let me find that photo for you. I know I favorited it.”
This use is relatively new and is not common in academic or formal contexts. Favorite is more frequently an adjective (e.g., “my favorite shoes”) or noun (e.g., “These shoes are my favorite”).