A Bit Disappointed with the G5X

How small is this flower? It is a bit hard to tell without context but I am guessing it is very tiny, and you are as close as the camera's minimum focus will allow?

If that is the case, it is tough for most lenses to get the best results wide open for "macros", especially these large sensor compacts (and the rx100s struggle as well). That said, this is a particular weakness of the g5x/g7x lens. It tries to do a lot of things, and as a result it does not do wide open macros well, resulting in low contrast, halos, etc. I usually stop down to f2.8 for wide "macros", and f4 for tele "macros". The depth of field is usually pretty narrow and makes it tougher to nail focus anyway. To compound the issue, I have heard some people finding that when shooting these shallow macros, the camera will misfocus slightly to the rear, but I have heard that strangely enough, face detect autofocus helps this issue.

As for the noise- it does not look great. My thoughts on the sensor is that it is tuned to give good results at high isos, which often sacrifices some smoothness at base iso. Mine doesn't do a great job on smooth areas like sky and walls either, but looks better than this, I think. If you have a chance, maybe go to a store to shoot a similar shot with your camera and a display g5x/g7x to see how they compare- if they are much different, the sensor could be subpar. If that is not practical, try shooting a raw+jpeg to see if the raw looks substantially better, which would at least let you know if any jpeg settings are a problem. I set my noise reduction to "low" which is good for me, but you may want to play around with the options. The g7x ii also added much more control over sharpening, etc. which could help to get the results you want.