MDPI is widely recognized as a large open-access publisher operating on a peer-review model, making its basic definition as an open-access academic publisher common knowledge.
The claim simply defines MDPI's well-established publishing model and industry classification. While there is ongoing academic debate and criticism regarding aspects of its publishing volume and peer-review rigor in certain journals (as discussed in paper [0]), the definitional statement that MDPI operates as a peer-reviewed open-access academic publisher is a matter of common knowledge and organizational description.