Why is Bracket Pair Colorizer 2 in Visual Studio Code not working for some files in WSL but is working for them in Windows?

I'm using Ubuntu WSL and VSCode. I am using the extension Bracket Pair Colorizer 2.

In Windows, the extension works fine and colours all my brackets, including in .sol files.

On WSL, it still colours brackets for .js and .css and others, but .sol files have uncoloured brackets.

Any idea why this might be? I can't find any settings that seem to control this.