> Interstate commerce would allow congress to make such a law. However, the real question will be if congress gave or intended to give the FTC the authority to perform this action.

That's my take as well. There is almost certainly no doubt that the commerce clause (under current precedents since the 30s) gives Congress the authority to make legal rules like this one. If there be doubt here then it will be about a) the ability of Congress to delegate this power with b) such a vague and all-encompassing term as "unfair" to describe the practices that the FTC may regulate, and/or c) whether this particular rule violates the "major questions" doctrine found in the recent W. Virginia vs. EPA case.