No. Bowl water level can be influenced by the connected drainage arrangement, and the pump cannot be diagnosed from that observation alone.
What the observation means
A low level, gurgling and returned water are different symptoms. The installation and trap arrangements may need professional consideration.
A useful next step
Record when the change occurs and which connected fixture was last used, without repeated tests. Seek assessment if it persists. Do not alter venting, fit improvised valves or block openings to restore the visible bowl level.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.