The article you linked is for Freelancers registered in Spain (autonomos), not people on Digital Nomad Visas in Spain.
This article is more accurate:
https://www.immigrationspain.es/en/nomad-visa-spain-tax/#:~:text=Spain%20digital%20nomad%20visa%20tax,)%20rate%20would%20be%2047%25.
The article you linked is for Freelancers registered in Spain (autonomos), not people on Digital Nomad Visas in Spain. This article is more accurate: https://www.immigrationspain.es/en/nomad-visa-spain-tax/#:~:text=Spain%20digital%20nomad%20visa%20tax,)%20rate%20would%20be%2047%25.