Upgrading from 1.23.1 to 1.24.0 adds unwanted underlines and italics to Monaco

[haines]

Validations

• Follow our Code of Conduct
• Read the Contributing Guide.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.

Describe the bug

After upgrading shiki and @shikijs/monaco from 1.23.1 to 1.24.0, whitespace became underlined and braces and brackets became italicized in our Monaco editors displaying YAML or JSON (using dracula-soft theme).

The same effect was not present in our static code blocks (which render with codeToHast and hast-util-to-jsx-runtime).

In the below screenshots you can see a Monaco editor on the left and a static code block on the right. Prior to the upgrade, they looked pretty much the same (except Monaco has colorized brackets).

1.24.0

1.23.1

Reproduction

https://github.com/haines/shiki-monaco-1.24.0-underlines

There are two branches in the repo, 1.24.0 (the default) and 1.23.1. Run with

pnpm install
pnpm run dev
open http://localhost:5173/

Contributes

• I am willing to submit a PR to fix this issue
• I am willing to submit a PR with failing tests