Brexit has damaged Anglo/Spanish relations. This is not just some sweeping statement, I think you can safely say that Spain was not too impressed when Britain decided to leave the European Union.
I found myself in the difficult position of having to explain to immigration staff at Madrid airport that I was a resident in Spain while they claimed that my green residence certificate was no longer valid. The official advice is that the certificate is still legal but it is better to have one of the new TIE cards.
Some people are saying that the issue over British driving licences in Spain is being held up because of Brexit-related problems. At the moment British driving licences for British residents of Spain are no longer valid and this is causing all sorts of problems despite the best efforts to the British Embassy, which is trying to get the issue resolved. The list goes on.
The fact that British passports have to be stamped when British citizens arrive in Spain is also causing problems, especially as in some cases there are too few officers on duty to cope with the large number of passengers. If you think about it, it is quite normal that relations would be strained. Spain is a pro-European Union country and Britain is not.
It is a shame that all this has come about, but Spain needs to remember that it is heavily dependent on British tourism who could opt to go elsewhere if they are faced with too much red tape.