This is a patched version of https://wordpress.org/plugins/staticfeed/, which is no longer maintained on wordpress.org.
See the readme.txt for how this plugin is supposed to work.
The plugin creates static feed files under wp-content/staticfeed/.
Remove those files and then resave the plugin settings. The files should be recreated.
Now make a change to the rss2.xml file in that directory.
Then open https://yoursite.com/feed/ in a browser and check that the change is visible.
If it is, then the plugin and the redirect are working as expected.
You can also create a new post and see that appearing in the feed after publishing.