The BBC have dutifully tracked down someone from the UK who was asked to pay for treatment in a Spanish hospital to try and justify the EU Commission's interference in Spanish domestic affairs.
The NHS has to pay the cost of any treatment carried out abroad under the EU health insurance card system but the national health service of the country where treatment is being carried out bears the cost until it can be reclaimed.
The Spanish government is broke so it's hardly surprising that they're looking to cut costs. The EU health insurance card scheme is undoubtedly useful but it's expensive and bureaucratic and social security is a reserved matter for national governments. If the Spanish health service decides not to accept the card any more that's a matter for the Spanish government to decide, not unelected eurocrats in the unelected EU Commission or unelected judges in the EU Court of Injustice.