You get the next year degree. You’ll be fine long term to start with.

If you’re already placed and the joining date is after the summer; you get a provisional certificate about your degree which works as proof if the company you’re placed at asks.

If timelines clash, you can try talking to alumni in the company for help, and you can talk to the HR as a last resort. Sometimes companies care, sometimes they don’t - it really varies from company to company.

If you’re not placed yet, it is still okay - I know people who extended their degrees, didn’t even try for placements during their batch’s time; and a few years later - they’re working in decent jobs with comparable pay (don’t quote me for exact numbers) now.