Genuine question; is this a US thing? I've never, ever seen this or heard of it happening. I don't think I've ever worked at a company that didn't state in the contract the notice period. I have seen companies decide they don't want that person on site anymore when someone quits, but they gave "gardening leave"; the person goes home and is effectively on holiday, paid as usual, for their notice period.
There is a significant chance you will be instantly fired with no income for months.
US "at will" kind of thing? Must be.