Didn't you notify them you were sick?

I wouldn’t give a contract to a company surrounded by riots either. I hope you told them all thanks.

I mean, look at the bright side; getting written up doesn’t seem to matter much when your job is only gonna last three more weeks.

I believe the technical term for this is an "avalanche of shit".

Your employers are breaking the law. The government passed the Federal Cares Act which covers you. Here's a link to the information. Show it to your boss, and if the ball let them know you will be reporting them to the Labor Department, and possibly file a lawsuit. you will win. https://www.uc.pa.gov/COVID-19/CARES-Act/Pages/default.aspx

Your boss can’t write you up for quarantining while you have Covid. That’s not legal at all. And the fact that you’re losing your job in three weeks sounds like he’s trying to find reason to terminate you in those three weeks with reason of attendance or write ups instead of downsizing so you won’t get unemployment. Take it to HR immediately with proof of your diagnosis.