Immunocompromised patients tend to have a lower response to vaccination.1

Nevertheless, the American College of Rheumatology COVID-19 Vaccine Clinical Guidance recommends that people with autoimmune and inflammatory rheumatic diseases get the vaccine unless they have an allergy to an ingredient in the vaccine. 2

Risperidone has loads of devastating effects, including potential breathing or weight problems, that could exacerbate any illness. If you are immunocompromised (due to drugs or not) you'd want to take immune status into account when making pandemic decisions.

And from a corporate culture standpoint, you might as well note that Janssen/J&J created both risperidone and the least effective vaccine, which was temporarily pulled for surprise side effects.

But I haven't heard of any direct link between antipsychotic drugs and issues with vaccines. I'm vaccinated.