  In this study the cross-correlations between the cryptocurrency market
represented by the two most liquid and highest-capitalized cryptocurrencies:
bitcoin and ethereum, on the one side, and the instruments representing the
traditional financial markets: stock indices, Forex, commodities, on the other
side, are measured in the period: January 2020--October 2022. Our purpose is to
address the question whether the cryptocurrency market still preserves its
autonomy with respect to the traditional financial markets or it has already
aligned with them in expense of its independence. We are motivated by the fact
that some previous related studies gave mixed results. By calculating the
$q$-dependent detrended cross-correlation coefficient based on the high
frequency 10 s data in the rolling window, the dependence on various time
scales, different fluctuation magnitudes, and different market periods are
examined. There is a strong indication that the dynamics of the bitcoin and
ethereum price changes since the March 2020 Covid-19 panic is no longer
independent. Instead, it is related to the dynamics of the traditional
financial markets, which is especially evident now in 2022, when the bitcoin
and ethereum coupling to the US tech stocks is observed during the market bear
phase. It is also worth emphasizing that the cryptocurrencies have begun to
react to the economic data such as the Consumer Price Index readings in a
similar way as traditional instruments. Such a spontaneous coupling of the so
far independent degrees of freedom can be interpreted as a kind of phase
transition that resembles the collective phenomena typical for the complex
systems. Our results indicate that the cryptocurrencies cannot be considered as
a safe haven for the financial investments.
