Boost may be time limited or reduced under conditions described by the manufacturer. It is not necessarily intended to remain active for the entire cooking period.
What the observation means
The pan, selected zones and heat conditions can affect availability. A normal return to a stated level differs from the hob shutting down with a fault message.
A useful next step
Check the programme's limits and note the elapsed time. Do not repeatedly reactivate boost to defeat the intended restriction. If it ends immediately with suitable cookware under permitted conditions, record the full display message for assessment.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.