"Whataboutism is a variant of the tu quoque logical fallacy that attempts to discredit an opponent's position by charging them with hypocrisy without directly refuting or disproving their argument"
(Sorry to essentially say the same thing multiple times over, but hypocrisy is so engrained in our dna you need to forcefully call attention to it sometimes.)
That's really the danger of whataboutism, it basically asserts that any two actions must be considered morally equivalent, regardless of the intended aim. That is simply not the case.