[Compiler Bug]: Unicode characters handled incorrectly

[JCown]

What kind of issue is this?

• React Compiler core (the JS output is incorrect, or your app works incorrectly after optimization)
• babel-plugin-react-compiler (build issue installing or using the Babel plugin)
• eslint-plugin-react-compiler (build issue installing or using the eslint plugin)
• react-compiler-healthcheck (build issue installing or using the healthcheck script)

Link to repro

https://playground.react.dev/#N4Igzg9grgTgxgUxALhAgHgBwjALgAgBMEAzAQygBsCSoA7OXASwjvwFkBPAQU0wAoAlPmAAdNvhgJcsNv3H5F+ADxcAwhAC22OgjoFcGXAF5RIAO4JKcLQnyBeDcDSO2fwB6AHwL8ggNziAvuJBulg4BDZ0YATqWjp6BMb4-JgwEJhgwsbuIl5SMjBsyoRMAG7uwClpYAB0hui4-g6Oyq7FZQEg-kA

Repro steps

When passing a unicode character as a prop, like <MyComponent text="welcome 👋" /> then in RC output code we can see <MyComponent text="welcome \uD83D\uDC4B" /> - unicode character gets replaced by "stringified" UTF-16 representation of it.

Expected result (on the screen)
Welcome 👋

Actual result:
Welcome \uD83D\uDC4B

How often does this bug happen?

Every time

What version of React are you using?

19.1

What version of React Compiler are you using?

19.0.0-beta-ebf51a3-20250411