Gotta be San Francisco rates, or a very fancy place. Nicer daycares (usually Montessori schools that also take kids under a year) in our US city are around $900-$1200/m. Less-nice, $700-900.
Out of curiosity, I did some spelunking. The US Department of Labor has stats[0] which summarize county-level "median yearly prices for one child at the market rate." Still TBD what the comprehensive data show at P99. That said, among the county-level medians, it appears the maximum estimated cost in 2023 is in Arlington County, VA, at $28,747 for a single infant, which is $2400/mo.
This depends on the age of the child, of course. If you want them looked after full time from 6 months it's a lot more; if you want them in after school club when they're 7 so you don't see them til 6pm then it's much less.