Is it right or wrong for the poster to be signed as a participant?

That's right. In the signature of a poster, there is usually a list of people involved in the production of the poster, including designers, photographers, editors and so on. The names and positions of these people should be listed accurately to show their role and contribution in the production of this poster. If the range of participants is not listed in the poster, or the listed range is incorrect, it may give people an unprofessional or irresponsible impression. Therefore, it is an important detail to ensure the correct range of participants in the poster.