baked combined lighting with cycles in 3.6 , map with 15.000 faces. I should have not merged objects with the map. The maps should be like 5000 faces max. Even 4K texture is not enough to avoid noise 
Connect the Image texture to the Ambiant input in the Extended Material node … do not make the common mistake to mix or multiply it with the Diffuse texture. Mix or multiply with black gives black and you dont get your colors back even with more light.
Below, i still mix the 4K texture with the diffuse texture but on “Soft Light” mode … which seems to act like a true light source. It seems the best option. I recommend
Below, baked AO with internal Render engine on RayCast mode