Tree shaking not working with Next.js 14, 15 & React 18; Request support for React 19

[nguyenvanhieu1996]

Summary

Tree shaking does not seem to be working when using Next.js 14, 15 with React 18. This issue causes unnecessary bundle size increases and potential performance issues.
Additionally, we would like to request support for React 19 in future releases.

Next.js Version: 14.2.24 / 15.1.7
React Version: 18.2.0
Polaris Version: 13.9.2 (latest)
Build Tool: Webpack 5.97.1

Expected behavior

Tree shaking should properly remove unused code when using Next.js 14, 15.
React 19 should be officially supported.

Actual behavior

Unused components and utilities are not being eliminated during build time.
Performance may be affected due to larger bundle sizes.

Steps to reproduce

Set up a new Next.js 14 or 15 project with React 18.
Install @shopify/polaris and import specific components.
Check the final bundle size with Webpack.
Observe that tree shaking is not working as expected.

If relevant, provide code snippets or configurations.

Are you using React components?

None

Polaris version number

No response

Browser

No response

Device

No response