Maybe you solved it by yourself, but this is the workaround I just found out:
1. Go to section “Accepted Filenames & Rejected URIs” which you can find in the advanced tab in WP Super Cache Settings.
2. Add the string: “/wp-json/wp/v2/” without the quotes in the text area.
3. Press the Save Strings button.
Now it won’t try to get a cached version of a REST API endpoint.
The alternative is to check the option “Don’t cache pages with GET parameters. (?x=y at the end of a url)”.
