High memory usage after time machine restore

Okay, so I upgraded to catalina and then found out one of my programs wouldn't work with it. I then restored from a backup to go back to sierra. Originally, sierra and catalina would idle anywhere from 3 to 4 gigabytes. Now, it idles at 8-10 gigabytes. I have a 2012 mac mini with 16gb of memory, but I'm wondering why its idling higher now? Would it have to do with the recovery partition being catalina instead of sierra? Any help is appreciated. Its been about a day now since I restored.