It was a multitude of reasons, Twitter being in the hands of Elon (who pushed the hashtags #genocidejoe and #holocaustharris, but I wouldn't be surprized if he also misinformed people about the election dates), other social media stopped enforcing their community guidelines to be "unbiased", media was way harder on Kamala than on Trump (including the downplaying of the mental decay and insanity of Trump), the whole "let's try to appeal to moderate conservatives" thing, etc.