The cooker manufacturer's clearances and ventilation openings must remain respected. A new wall finish can change the space available even if it looks purely decorative.
What the observation means
Heat resistance and access to connections are installation questions. A sheet fitted over a rear slot or an altered gap can affect the appliance's intended arrangement.
A useful next step
Tell the fitter and service team about any new heat or airflow symptom after the work. Do not drill the cooker or seal its rear openings to secure the splashback. Repair assessment and changes to the surrounding installation should be planned separately.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.