clear images on auto, noisy images on manual

I have a Canon S50 pocket camera. It has a full manual mode, but I
found that images are very "grainy" in the manual mode, even when I
would make all settings exactly the same as get set in auto. To avoid
that I would just set the camera to P and adjust the white balance
with + and -.

The camera just got busted, and I need a new pocket camera. I've been
happy with the S50, except for the above bug. Does anyone know what
causes that, and if newer Canons still have it?