I don’t think that Brexit had any effect on bitcoin because it mainly concerned on the european union and does not entirely touch on crypto. Those affected by Brexit are those doing business within Britain and the other countries part of the EU because of the tariffs.
Based on my opinion, if a crisis will happen to a country of the major holders of bitcoin maybe we can see the price of bitcoin to drop very fast, if something happen to the economy of US, China, and UK maybe bitcoin will be dead, they are the major countries that supports the supply and demand of bitcoin.
I guess if a financial crisis occurs which would greatly affect the bitcoin users in a country that contains or controls a huge volume of bitcoin, then this may have some effect on the bitcoin price. Especially for countries like China were there is a majority of miners. Just like how if a ban will be made in countries like this, it may affect the price negatively.