Well, the crypto market as a whole is always moving in unison (to a certain degree).

I think that you have to realise despite the fact that people think bitcoin is dead, it is still the first and foremost thing that comes up to the public's consciousness when you mention the idea of crypto. So its price action dictates how much money is flowing into crypto overall.

I think that this trend will improve as a matter of time though, you're not going to see as much correlation between BTC and alts going forward because how much alts have developed.