There are many, many adverse influences of Brexit on the UK. As related to my concern, researchers in the UK are going to be purged from international studies in the EU.
The Guardian: UK scientists dropped from EU projects because of post-Brexit funding fears
Funding is an annoying issue for most researchers. Many academic studies need a considerable amount of money. Different from industrial activities, it is not guaranteed at all that a certain study will make a profit in the future. A few studies will be a nice investment, such as successful medical drugs, but others will consume time and money in vain.
Therefore, it is not easy for researchers to get the budget for their favorable studies. The government and some companies offer to fund for research. But most of them are so competitive that many researchers have to abandon to prove their hypothesis because of lack of money.
Previously, UK scientists can apply to EU fund as well as domestic ones. But it may be impossible if Brexit is established. There are many researchers other than British to be eager to win the fund.
Basically, scientists do their work from the global point of view. Many of them discuss their region of study with foreign researchers. While most popular academic journals are written in English, the nationality of the authors is very various from the US, Europe, to Asia and other countries. Recently, I frequently see studies from developing countries.
Considering the current situation, it is essential for many researchers to achieve international studies. Brexit will make British researchers difficult to gain funding opportunity in the EU, leading the decline in academic performance in the UK.
Furthermore, Brexit will do damage to administration of universities in the UK. K universities accept many students in the EU. They pay the tuition, which is one of the sources of income of the university. If EU students become difficult to enter a UK university because of Brexit, the financial status of the universities will be deteriorated. It is a nightmare for the UK, as a nation one of whose resources is intellectual property.