You will not be able to leave a comment anonymously when pledging on a project.

When you pledge on a project you will have the ability to comment and your name will always be visible next to any comments you have made, even if you pledge anonymously.

Users on the site will be able to click on your name next to any comment you have made and view your public profile.

If you did not want to comment publicly, you can remove your comment by following this guide.
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