That's true of March, but if you look at the big picture the US always vetos on the side of Israel's political interests (until the most recent one, which Israel didn't obey anyway). This was going on long before the current genocide.
The US has recently been trying to lobby the ICC on behalf of Israel (neither country are member states). Its support is a big part of why we can't just step in and start enforcing international law eg the Geneva Conventions.