it's also the case that some groups have become hyper-vigilant about academic "cancellations" in the last several years, which could account for why so many purported incidents have occurred since more attention is being paid to the issue.

I don't see any evidence that this spreadsheet is the result of someone systematically reviewing every case of a professor or other academic being dismissed, rebuked or whatever since 2014, so I don't really see how it could constitute a trend.