Debug IDs are detailed in the TC39 proposal.

Debug IDs are unique IDs generated from a deterministic hash of the source code which are then injected/included in both source and sourcemap. They can be used to easily identify the correct sourcemaps in production.

I've recently added support for injecting debug IDs to webpack, Rollup, and Rolldown and wanted to get them working in esbuild too but I don't really know Go yet!