Lower return

Hi there everybody. I had two jobs during 2021. I already filed a W-2 for 2021 but I forgot to add my second jobs W-2 so I went to amend and add that and it’s saying I owe about 500 which would mean I wouldn’t even be getting anything for my second W-2 as I started that job late 2021. In 2020 I had 2 jobs for that year and adding a second W-2 made my refund go up a bit. I’ve never had to owe money on my taxes. Why could this be? Am I making a mistake? Is there a mistake?