Is it illegal to park your car in the community and paint it by the property?

Of course it's illegal. Violation of property law and civil law.

Article 36 of the Property Law causes damage to real estate or chattel, and the obligee may request to repair, redo, replace or restore it to its original state.

Article 37 If the infringement of property rights causes damage to the obligee, the obligee may demand compensation for the loss or bear other civil liabilities.

Article 38 The methods of protecting property rights stipulated in this chapter may be applied separately or in combination according to the situation of infringement of rights.

Infringement of property rights, in addition to civil liability, in violation of administrative regulations, shall bear administrative responsibility according to law; If a crime is constituted, criminal responsibility shall be investigated according to law.