There are a number of countries now adding a restriction of 8 months or 270 days from the point when you are fully vaccinated - the suggestion is they can't be sure vaccines are effective beyond that kind of time period.
The current restrictions in timatic don't seem to make any distinction between mainland Spain and any islands, and just say:
3. Passengers arriving from the United Kingdom must have:
- a negative COVID-19 NAAT test taken at most 72 hours before arrival. Tests accepted are: CRISPR, HAD, LAMP, NEAR, PCR, RT-LAMP, RT-PCR, SDA and TMA. The test result must be in English, French, German, Spanish or accompanied by a certified Spanish translation; or
- a COVID-19 vaccination certificate showing that they were fully vaccinated with AstraZeneca (Vaxzevria), Janssen, Moderna or Pfizer-BioNTech, Serum Institute of India, Sinopharm or Sinovac at least 14 days before arrival.
This does not apply to:
- passengers younger than 12 years;
- deadheading crew.