Do not assume that altering a tablet preserves its intended use. Follow the detergent maker's instructions and the appliance's dosing guidance for the selected programme.
Understanding this situation
Layered products, coatings or dissolvable packaging may not be designed for cutting, and exposed concentrated detergent requires careful handling. A small load does not automatically mean an arbitrary fraction is appropriate.
A useful next step
Use a product and dose suited to the task as instructed. Keep detergents away from children and avoid mixing alternatives. If results are poor, report the actual product and amount rather than concealing that it was modified.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.