The maximum drum rating is not a universal load limit. Particular programmes can require extra room, reduced agitation or a different rinsing pattern, so their permitted amounts can be much smaller.
Understanding this situation
Treat the programme table as the working limit for the cycle you intend to use. A bulky load can also fill the drum before reaching the stated weight. The useful distinction is between a quantity that fits through the door and one that can move properly during the selected treatment; these are not necessarily the same.
A useful next step
Check dry laundry weight where the manual specifies it, and do not compress items into the drum to fit an optimistic capacity figure. Keep enough room for the programme's intended movement. When results deteriorate only on a specialist setting, compare that setting's own capacity and fabric suitability before assuming the machine has lost washing power.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.