Macintosh HD Filling Up Rapidly - 80gb Overnight

Hi. I have been looking at the Get Info window for my Macintosh HD on my iMac. Yesterday it showed about 175gb free and today it has dropped to 91gb. I have not knowingly downloaded anything that would approach that amount of space. Since i don't have a baseline it's difficult to figure out where this additional space has gone. I did not see this type of issue before upgrading to Catalina. I upgraded several weeks ago.

Thanks.