I have encountered the opposite of this. All of the latest pro tier models are still fighting for their lives to use powershell correctly, really basic things like quotes, escaping, heredocs. Doesn't matter what I put in agents.md or instruct it to do. You just have to accept the token tax of it stomping on rakes until it figures it out itself and then keep using that session.

It's bad enough that I've considered writing some sort of cursed bash->posh translation layer

Yet it has no issues at all implementing and then writing slopjective-c 3.0

Opus 4.6 has gotten pretty good at writing Powershell.

It’s the first model where I didn’t have to ask, repeatedly, that it use Powershell 5, and never use emojis or other invalid characters, like Gemini and those non-ASCII spaces.