But what is the reason for this?
In my opinion, because of the war, most people avoid high-risk assets such as bitcoin and other digital currencies!
+How many wars have Bitcoin experienced so far?
-Nothing
So it is natural that most people, because they do not know the reaction of bitcoin, turn to other assets such as gold and oil. The escalation of the conflict between Ukraine and Russia will also cause more fear among investors.
As @Pmalek said above, Russia is a big player in the crude oil market, they are the 2nd largest crude-oil exporter in the world. If one the biggest players in a global market is on its way out of the market because of sanctions, demand of this global commodity will naturally go up. Look at Natural Gas and Wheat prices, exact same story as the crude oil because of Russia and the sanctions.
Maybe it is also that traders are selling Cryptocurrencies to quickly get into Oil investments?
a smart trader doesn't go jumping around from one asset to another asset selling them left and right because of price crashes or sudden spikes.