just like "political correctness" is a meme crafted to make liberals behave more like rightwingers, so too is "cancel culture" a meme crafted to make leftists behave more like rightwingers.
it's meant to police personal expression and deny accountability.

"political correctness" as a meme was invented to demonize a fully positive act - extending respectful conduct and decency to marginalized groups, for example by being more mindful in your language.
the right reframed this as an orwellian stifling of free speech.

meanwhile "cancel culture" as a meme works by combining fully positive acts with negative acts into a singular unified concept. (even though the individual parts hadn't been thought of as being part of a greater whole before.) it establishes false equivalence between good and bad

if you ask people what cancel culture is, everybody has a different definition. because it incoherently lumps together distinct kinds of behavior

cancel culture is simultaneously:
1. saying you think somebody did something bad to your peers
2. speaking truth to power
3. prolonged, vicious harassment campaigns

the first two points are good and valid. but by positing they're the same thing as harassment, because it's all "cancel culture," you condemn both people who voice their displeasure and the less powerful holding the empowered accountable

since the individual components of "cancel culture" are their own distinct things, we already have perfectly good ways to talk about them.
if somebody has a good-faith discussion about how they think somebody's else idea is wrong, don't call it "cancelling."

if somebody informs a large audience about the crimes of a celeb, don't call it "cancelling."

"cancel culture" should be deleted from your vocabulary, at least in an unironic sense.