As of writing (Sept. 10, 2020), this extension does not function at all.

Reproduction steps:
- open any public repository
- open any pending pull request and choose any file it modifies
- open that file on target branch
- use extension to view the "potential changes"
Result: I see "There are no pull requests in this repository. That means there are no changes related to this file."
Since I explicitly chose a file with "potential changes", the data this extension reports is definitely incorrect.