I recall a former co-worker who inflicted toxic positivity on myself and others on our team. Anytime someone on the team was struggling with something - personally or professionally - and needed to vent a bit of frustration or irritation, she would peddle the belief that all we needed to do to feel better about it was change our outlook to be less 'negative.'
Don't get me wrong, mindset is a powerful thing. But this became such a trend that people simply stopped having honest conversations with her because they knew the frustrating response they'd receive in return. It stunted the growth of any meaningful connection with her because we felt the need to always keep things positive which also meant keeping things very surface-level. You can't develop authentic relationships with someone when you feel like you have to censor the tough stuff, which is precisely where deep connections are built.
It's all about balance. Things can't be sunshine and rainbows all the time. Hard things happen in life and, when they do, humans just want to be heard and seen rather than dismissed or labeled as negative.