There's a new book on this subject - "Toxic Positivity: Keeping it Real in a World Obsessed with Being Happy" https://www.amazon.com/Toxic-Positivity-Keeping-World-Obsess...

I also found these articles/posts to be pretty decent: https://www.verywellmind.com/what-is-toxic-positivity-509395... https://thepsychologygroup.com/toxic-positivity/ https://www.wsj.com/articles/tired-of-being-told-cheer-up-th...