@clarnx, they’re already using node-fetch: liontime-api-redirect/index.js at main · Chun-gu/liontime-api-redirect · GitHub
I can see this happen with @jacobus91 in this thread too: Netlify Fetch Function Works Locally, Returns 502 Error Deployed. Even they are using node-fetch and getting the exact same issue.
@Chun-gu and @jacobus91, could you try using axios to see if it helps? But, please use Axios v1.1.3 or lower as v1.2.0 of Axios currently has a different bug: https://github.com/axios/axios/issues/5298