When you create a custom feed, it is visible to all the users of your Leadfeeder account by default.
In other words, if you and/or your colleagues are users of a Leadfeeder account for your company website, then everyone will have access to all custom feeds.
If you have our GUARD add-on, you can also create custom feeds and give view-only access to other users for the feed. You can read more about this add-on here.