The mark of cancel culture, in my view, is that the criticism leading to cancelation is motivated (usually subconsciously) by jockeying for status.
If being woke is good, being more woke is better, and the way to show off your level of wokeness is by expanding the range of things you can artfully diagnose as being oppressively offensive.
The same psychological dynamic is present among, for example, religious fundamentalists -- there's a sort of contest to see who can most strongly signal loyalty to the in-group by believing transparently crazy things.
When you believe something because it's actually true, that's not fundamentalism. When you disaffiliate with someone because he's actually bad, that's not cancel culture. Those things have very little signaling value to any particular in-group.
But when you disaffiliate with someone because you think doing so will raise your status among your (usually left-leaning) in-group, that's what I'd call cancel culture.