Notwithstanding the foregoing, in the event proffered conditions include a requirement for the dedication of real property of substantial value, or substantial cash payments for or construction of substantial public improvements, the need for which is not generated solely by the rezoning itself, then no amendment to the Zoning Map for the property subject to such conditions, nor the conditions themselves, nor any amendments to the text of the zoning ordinance with respect to the zoning district applicable thereto initiated by the Town Council, which eliminate, or materially restrict, reduce, or modify the uses, the floor area ratio, or the density of use permitted in the zoning district applicable to the property, shall be effective with respect to the property unless there has been mistake, fraud, or a change in circumstances substantially affecting the public health, safety, or welfare.