To shine a little more light, what you're referring to is called a minimum advertised price policy, or MAPP.
And as you've stated, it's done by anyone who publishes a MSRP.
https://www.deltafaucet.com/for-professionals/product-resour...
https://assets.ctfassets.net/zlhl2y58oyef/3wENIXr7qvqyOoVD6R...