Looking throught nodejs sdk docs, I found that the api checks that the object is ~FileLike~ when attempting to append it to FormData. If it’s not FileLike, it gets interpreted as an object, which messes the key that gets added to the FormData hence the error.
My solution was to just set the values expected by the file like check on the blob and things seemed to work.
const blob = new Blob()
blob.name = "foo.png"
blob.lastModified = 20
I can’t include the link to the code as reference, but you can find it by going to the node js sdk on github, and looking for the function isFileLike. The code messing up is the function addFormValue.