Toxic positivity: the overfocusing on positive emotions and rejection of anything that makes you uncomfortable because it sends you "bad vibes" .

If you want to be perceived as a mature person, you have to acknowledge that the world is not a pink cloud with rose petals. And by shutting people down just because you don't want to get out of your comfort zone is not "being positive". Sometimes all this "positivity" becomes insincere, ineffective and leads to more harm long term.
Emotions are emotions, situations are situations, and they're not going away if you simply ignore them. You can categorize them as "good" or "bad" and try to improve them. But when someone addresses an important issue that seems negative, you can't respond with hugs and flowers and "stay positive". I will be positive when the bad issues get resolved. Clearly you wouldn't say that to victims of extreme abuse and clearly you wouldn't send "hugs and flowers" to some serial killer in an attempt to improve the world, because this does absolutely nothing! So until you have something practical to offer, at least don't belittle other people who are trying in their own ways.