Some hobs share available power between defined zones. A boost function may therefore limit a partner zone as part of normal management.
What the observation means
The pairing and restrictions vary by model. This is different from a random power loss or an electrical trip. The manual's diagram explains the intended relationship.
A useful next step
Record which zones and levels were active. Use the approved combination rather than changing installation limits. If behaviour differs from the documented pattern or a warning appears, report it. Do not attempt to bypass power management to make every zone run at maximum simultaneously.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.