Node.js 18 runtime transition and module resolution compatibility

Cloudflare Workers provides a compatibility boundary for Node.js APIs, allowing developers to target specific runtime versions. Transitioning from Node.js 16 to Node.js 18 introduces changes in how built-in modules are resolved and how the runtime handles fetch behavior.

When deploying in unbundled mode, the availability of specific Node.js polyfills varies. This creates uncertainty regarding consistent module resolution across different environments, especially when dependencies rely on implicit globals that may be absent or behave differently in the newer runtime version.

• Which specific Node.js built-in modules exhibit divergent resolution behavior between the 16 and 18 runtime versions?
• How does the transition to Node.js 18 affect the availability of polyfills in unbundled deployment mode?