Based on Binance article, it's from the Robinhood Markets Inc.
But I didn't find an answer that Robinhood confesses this accusation.

Whatever it is, it's expected that one day those big whales might sell their Bitcoin holding and could have an impact on the market.
However, if the Bitcoin price goes up, it will go up, because I'm afraid that traders and investors in the market will might react to the news.  If there is a perception that other large holders might follow suit, it could lead to a panic sell-off.