We're running into issues that are solved by node-fetch/node-fetch#671, which is part of the node-fetch 3.0.0 release.
I read through #118 and understand upgrading node-fetch to v3.x+ isn't on the short term roadmap.
Is there any consideration to upgrading using https://github.com/touchifyapp/node-fetch-cjs? Seems like it could be an easier upgrade path.
If it's something you're considering, I'm happy to help out/put up a PR!