No one said there isn't...No move is going to correlate perfectly 100%, but obviously a big part of crypto rise is because of all the $ printing of the last 10 years. Especially the last 2. It is a risk on asset, risk on assets largely trade in tandem.
If there is a real withdrawing of liquidity over a time horizon, I don't see BTC decoupling from that.
4th quarter 2018 market goes down 20%, BTC goes from 6500 to 3500 (wiping out my massive bet on Khabib vs McGregor at nitrogen fwiw)....Then Jan 2019 the fed pivots to rate cuts/ending bond selling, BTC steadily rises throughout the year just as the market does
Then 2020 the virus comes, everything crashes...Market goes down 35% in a month, BTC goes from around 10k to around 5k the same month.....Then they steadily rise in tandem until BTC tops in Oct 2020, the market tops in Nov...Both have had their gyrations but now at 10-15 month lows since.
If anything, as it becomes a mature asset, I think you could make an easy case that it is becoming more correlated.
The evidence for this is pretty overwhelming