The "entertainment" that people get from harassing other people.
I suppose this may be from my own experience, but I think it's sickening when you think about it for a while. The constant bullying you see on social media is often shrugged off and seen as normal now. People who make fun of others for appearance, interests, beliefs, and other harmless things. If it's one person, someone can just block them. If it's several users, it becomes too overwhelming to constantly block.
Suppose it's the anonymity of hiding behind fake usernames and pictures that gives people the encouragement to harass others. The lack of empathy in general that people have had since the pandemic in 2020 could also be recognized for contributing to this.