In eminent domain or inverse condemnation proceedings for any property within the area of the commission’s jurisdiction, in determining “just compensation,” as used in Section 19 of Article I of the California Constitution, or the compensation provided in Chapter 9 (commencing with Section 1263.010) and Chapter 10 (commencing with Section 1265.010) of Title 7 of Part 3 of the Code of Civil Procedure, the influence of the San Francisco Bay Plan, in effect at the time of the taking or damaging of the property, upon the value of the property or the interest being valued shall be inadmissible as evidence and not a proper basis for an opinion as to the value of the property.