TIDEWATCH satellite-derived bathymetry is a planning product. It is not an IHO-compliant hydrographic survey and it must not be used for navigation. This is stated in the product documentation, in the delivery metadata and here.
Achievable depth depends on water clarity. In clear water, useful results extend to roughly 20 m. In turbid or tannin-stained water this can fall below 8 m. TIDEWATCH reports the depth actually achieved for each delivery rather than assuming the nominal one.
Uncertainty is reported per cell, typically ±0.4 m. Use it. A depth without an uncertainty is not a measurement.