Arecent challenge to the european union created by a member state is?

A recent challenge to the EU created by a Member State (MS) is the Brexit.

The Brexit is the denomination given to the process that started in the EU after the UK (one of the MS) transmitted its desire to withdraw from the Union, after the celebration of a domestic referendum in which the 51.9 % of the voters supported the withdrawal option.

In 2017, the UK required the application of the Article 50 of the Treaty on European Union that regulates the withdrawals of MS. The UK is due to leave the EU on 29 March 2019 at 11 pm (British time).

the above statement/question is (true);

this is called police cynicism. i hope this .