22k net is a lot more than most people in Murcia earn. With no rent or mortgage, you should be fine.
It's a lot more than most of my Spanish friends earn.. But then most British immigrants wouldn't like to be living in a small piso in the town centre in a not very attractive apartment block...or in a rundown campo finca.
Most of my Spanish friends don't eat out regularly, dread the water and electricity bills, an urgent dental appointment or a necessary car repair.
That's not the kind of retirement most UK immigrants to Spain want.
The 22k euros is I'm guessing based on the current exchange rate. We don't know how many people that 22k euros has to cover.
But currently it's an income of lessthan 2k a month and may well shrink if the £sinks again.
That may have to cover IBI, house repairs and maintenance, car repair and maintenance, possible future health insurance depending on Brexit negotiations, tax deducted, utility bills, replacement of domestic items, dental care and so on....before you put food on the table.
So much depends on your expectations and the kind of lifestyle you wish to enjoy.
And of course on the kind of Brexit the UK manages to negotiate.....