Brexit will change British citizens when they want to stay in Spain. Probably, with the recient pandemic because of Covid-19, they don´t realize about the differences between before and after respect to travel to Spain. But when almost everything to come back to be “the same”, they will find out a lot of legal handicaps to stay in Spain. So, If I were you, I would look for a lawyer in Spain, for example, GM Lawyers.
Málaga and Costa del Sol are among favourite places for brits to stay long or short term. A year ago, this was not a problem but since January 2021 everything is being different.
How many days can I stay in Spain after Brexit
Depend on what British people want to do. If you are a British citizien and you travel to Spain, you must know that you can not be there more than three months. If you want to stay longer, then you need to get tie card before arriving at Spain.
Other case is if you want to get a job or if you have applied for a job before arriving at Spain. You can work. However, you must bring Spanish work visa with you from a national embassy or consulate. Remember, you must do it before getting to Spain.
These are general questions but the best advice I give you is you must be back up by a lawyer. The situations can look similar but really they are different cases. And Brexit is a new situation with new rules, so lawyers are the best people that will get up to date to you about staying in Spain after Brexit.
"I want to make a permanent move"
If you want to make a permanent move to Spain after Brexit, then the situation changes respect to stay for short term. Definitely, you must be helped by lawyers. It is necessary to study your conditions, for example, your age, your employement status and other factors. If you don´t want to be in legal troubles, the best recommendation is contact to GM lawyers.