Is it illegal for someone to take photos with the office door open?

May infringe the portrait rights of others.

The law stipulates that no citizen’s portrait may be used without his or her consent. Portraits and documentary photography that are taken without the consent of the portrait rights holder cannot, in principle, be published or exhibited, even if it is a purely non-profit exhibition.

Illegal criminals, dishonest persons subject to execution, online advertising fraud, counterfeiters, etc. can expose their photos and videos, which does not constitute "infringement of portrait rights."