You probably had to spend something to qualify for the sign-up bonus, but there's no definite connection between deductions for what you spent and the $1,000.  You could have met the spending limit in December 2023, then received the reward in January 2024 and canceled the card in February 2024.  Report it as "other income," but are you sure the bank is not issuing a 1099 to your SSN?  (They have another week to do that, you know.)