Is it legal for developers to make false propaganda to reduce property fees?

Illegal. According to the property management regulations, it is the responsibility of the property management company to collect property fees, and developers have no right to make a promise of "reducing property fees" in advance. Developers do not have this function, nor do they have this authority, nor can they realize it (property fee exemption). Even if the price is reduced under the guise of "property fee reduction", it is illegal to adopt this method in publicity.