Yep, they use a four-level system, with Level 1 having no restrictions, and Level 4 having the most. The situation is evaluated on regular intervals, so things are changing constantly. Tenerife, Gran Canaria, La Palma, and La Gomera are currently at Level 4; and Fuerteventura, El Hierro, and Lanzarote at Level 3. But frankly, their restrictions are very mild and have barely any impact on enjoying your time there... Arrival controls are very smooth, as well.
I wanted to visit Fuerteventura mostly for its Mars-like landscapes