This is not a "callback"; it's a real crash.
Earlier, it was still fluctuating at a high level, but today it directly broke through the key level, indicating that the short-term bulls have been wiped out, and the sentiment is starting to weaken.
Pay close attention to whether $BTC can hold above 70,000 today; if it can't, it will continue to look for support downwards, fluctuating in the range of 68,000-65,000; then there's $ETH, which may break below 2,200 (clearly showing a weak structure), and the altcoin sentiment is also starting to decline.