IMO the main issue with cancel culture is when it targets people who are innocent or gives unreasonable punishments for small mistakes. Those being cancelled are tried in the court of social media, where critics attack without evidence or even knowing the accusations. The accused' friends and employers fear being associated with the accused, even if they ultimately get cleared of any wrongdoing, and they can sue for defamation but it won't necessarily work out.

People have gotten kicked out of colleges for using racist words in text messages. People have been fired for their jobs for messages taken out of context. Non-public individuals start getting death threats online and they get called out in the streets, for small mistakes or things taen out of context.

A separate issue is that people sometimes get cancelled for things that happened a long time ago, sometimes even when they were still young. The issue here is that people change. It would be like boycotting a company because 20 years ago they exploited workers, regardless of whatever they're doing today. It's a really grey area.