It’s more complicated than that. Arm is still subject to US sanctions because they use US tech.

There’s this whole drama with Arm China, which was effectively stolen from Arm’s control. I haven’t followed it super closely in recent years but here’s some recent news

https://www.tomshardware.com/pc-components/cpus/arm-wants-to...

But they maybe subject to that de minimis rules that the US used to block technology that uses some of theirs inside. Right now is 25% of the tech inside that trigger export rules IIRC