I must be misunderstanding this one. That sounds like you want a person that buries their feelings and pretends to be joyful all the time. It's perfectly human to have a bad day and on occasion be a little shitty.
If you're speaking of them being shitty most of the time about most things then I can see your point.
Edit: Grammer is important when trying to communicate without misunderstanding.
Why would I be talking about the first one? Toxic positivity is complete and utter bullshit, and I'm tired of people telling me I can't complain about other people for whatever reason.