luma.gl/docs/developer-guide/editing.md

Editing

Shader Syntax Highlighting

For practical reasons, luma.gl stores GLSL and WGSL shaders inline in strings, rather than as separate files. A major drawback with this approach is the lack of syntax highlighting.

If you are using vscode, the vscode-glsl-literal and vscode-wgsl-literal vscode extensions can be used to regain syntax highlighting.