There's two thoughts with this. And this might be a negative view here.

1. You were supposed to be reporting side gigs anyway... a lot of people didn't, but that was still illegal. I've had to file a schedule C many years for side businesses and jobs. I know people who have boasted about enjoying side gigs because they "didn't have to pay taxes." These people are stealing from those of us who do pay taxes. And yes, I am aware taxation is theft.
2. People who are just paying people back for something/family/gifts and such are going to be a pain in the butt for everyone involved now. 🙄

I do hate this, especially when we have criminals laundering our tax money. Those who have abused the system, against those of us who actually do things honestly, might have a really bad day when they've made lots of cash and haven't set aside anything to pay for the tax liability of it. I don't know that I feel bad for them though, since I've had to do that every year. Since I don't know how much I might make in a year (usually below the quarterly threshold), I have them take more than needed out, which sometimes means big refunds and other times means some additional payments.