It is an outrageously cool thing to give money for an infrastructure project. They must have some faith that the government can deliver on something with $3.5 million. That would be two public toilets in SF, one toilet of which actually cost $300k in paperwork and so on despite two local businessmen signing up to have the work done.
Plot twist: the donation is from the owner of the company doing the infra project with the intention to launder money.
Money Laundering is really good with cash only businesses because you can just pretend you had 1000 more customers than you actually did.
But this money is going towards a high profile public works project with fixed outcomes. You might get ~5% of the money back clean, assuming the government is corrupt enough. Not to mention that its highly unlikely the government doesnt know who donated it. So theres really no "clean" money, its documented somewhere if investigators go looking.
The donator would be better off laundering through a car wash or corner store.
The "everything i dont understand is money laundering" crowd baffles me sometimes.