enforcement would probably happen at the level of the power utility. large mining operations have agreements with utilities to buy power at wholesale prices, the utilities know what the power is being used for

the real beneficiaries of this would be small miners (small business owners?) who either use their own locally generated power or the residential grid. oh, and all the people who don't mine in the US

    the utilities know what the power is being used for

I did not know this, sounds like something I would probably not do if I was running such company... why would utility company need to know what I'm using energy for..?

Depends how big your operation is.

A basic industrial unit with a 10 kilowatt supply? They'll supply you no-questions-asked.

If you're a huge operation like a steelworks, consuming tens or hundreds of megawatts, they'll want to work closely with you for capacity planning.

If you've got special business requirements, like a hospital or data centre that needs redundant, highly reliable power - you'll have to tell them that's what you need.

If you want to negotiate a discount below their normal prices, an account manager will sniff around your company to try and figure out how price-sensitive you really are.

If you want a big upgrade to your building's power, which needs new cabling installed or the road dug up? The workers might not keep quiet if they see you're a cannabis grow operation.

Because they need to forecast power requirements ahead of time. Maximum efficiency of resources is not just smart for greenhouse emissions it is smart for not spending more money than necessary to supply power.

Additionally, they need to know which clients to restore power to first (hospitals and essential services) and who can wait (commercial buildings on a weekend? Back of the line)

Note: it isn’t that they know exactly what the power is used for, but they sure know the general purpose (residential, industrial, critical service, tech, etc)

Companies have relationships with their large clients. They aren't just suppliers and more like partners in their business.

Maybe it's different in strict commodity markets but this knowledge also allows you for better cooperation. From little things like when to set service windows to large infrastructure investments for which you might want some buy-in before they happen.

Electricity is a limited and vital resources so usually it is tightly regulated who gets to use electricity. If the government doesn't like what you say you will do with the electricity then you wont get more than a typical home connection.

Companies might simply have to sign statements that they aren't doing forbidden mining, and in doubt auditors are sent.

So, private citizens are not subject to this potential law?

How would they audit and who would pay for it?

Where does companies revenue come from? Do they have servers in their data centers or obvious mining rigs?

Where I live you don't declare where revenue comes from, tax man only requires to declare how much revenue was made. Maybe it's not how it works in US? On the other hand I did not know there is specialized hardware you can only use for mining cryptocurrency, this would be clear evidence.

I wouldn't worry about it. The republicans can block it in the Senate for the foreseeable future, and I have zero doubt this would be an executive order that would be struck down by the SCOTUS the day after it was announced. I think it's safe to say that the SCOTUS is a rubberstamp for republican policies these days.