`lang=postcss` treated as `StyleContextUnknownLang`

[mikededo]

Before You File a Bug Report Please Confirm You Have Done The Following...

• I'm using eslint-plugin-svelte. (*.svelte file linting does not work with the parser alone. You should also use eslint-plugin-svelte with it.)
• I'm sure the problem is a parser problem. (If you are not sure, search for the issue in eslint-plugin-svelte repo and open the issue in eslint-plugin-svelte repo if there is no solution.
• I have tried restarting my IDE and the issue persists.
• I have updated to the latest version of the packages.

What version of ESLint are you using?

9.14.0

What version of eslint-plugin-svelte and svelte-eslint-parser are you using?

• svelte-eslint-parser@0.43.0

What did you do?

I'm running svelte-eslint-parser on a custom ESLint plugin for Svelte. I'm trying to detect Atrules inside <style> tags that are not marked as postcss. I'm getting the style context through the getStyleContext function, provided from the parserServices.

When running valid tests, the following code:

<style lang="postcss">
 /* ... */
</style>

Is parsed as:

{ status: 'unknown-lang', sourceLang: 'postcss' }

While it does not directly affect my development, is this the expected behaviour, taking into account that here lang=css is parsed through postcss.parse fn?

What did you expect to happen?

I believe it makes sense that lang="postcss" is parsed the same way non-lang tagged style tags are treated.

What actually happened?

{ status: 'unknown-lang', sourceLang: 'postcss' }

Link to GitHub Repo with Minimal Reproducible Example

https://github.com/mikededo/eslint-plugin-svelte-tailwindcss

Additional comments

No response