When Kamala went on The View and said that she wouldn't have done anything different from President Joe Biden. She got caught flat-footed and didn't have a answer to it. To many people, it made her look unprepared.
Kamala was criticized when she was asked about the U.S. relationship with Israeli Prime Minister Benjamin Netanyahu, when she gave a lengthy, somewhat circuitous answer that critics labeled "word salad". This was also the interview Trump sued over, and although that's not her fault, it did get hung on her.
When she cracked a beer with Colbert on his show, it was criticized as "forced" and "unpresidential".
During a rally with Oprah Winfrey, Kamala was asked a direct question about her plan to lower the cost of living. Her response was a two-minute monologue about "what is possible" and "commonality" which was widely ridiculed online for failing to provide a concrete policy answer.
Taken separately, maybe not all of these would draw so much attention, but they start compounding on one another and may have hurt her vote totals.
You may think none of these are flubs, which is your prerogative, but she did get criticized for all these. Not to put too fine a point on it, most would agree that these are the kinds of things a white male candidate can get away with more than a female candidate of color.
And, of course, the Charli XCX Brat thing didn't help, either.