Posted: Sat May 9, 2020 10:48am
It is as John says and the default setting post Brexit is that Brits will become non-EU citizens and Residencia requirements will increase substantially.
At some stage this will become part of the argy bargy of agreements the UK will try to reach with the remaining EU countries. This will include how Spaniards are treated in the UK and vice versa and, no doubt, Gibraltar and fishing rights, amongst others. Judging by the most recent meeting, everybody is still at the chest thumping stage, strutting about and squaring up to each other. This will get boring after a while and little by little we will find out what the future will hold for us.
It is up to you to decide where you want to spend most of your time and to arrange your trips within the restraints laid down. Not a bad quandry to be in really. :)
Edit: You may want to read Jim's Guides on the taxes you will be liable to pay if you become a Spanish resident.