How to fix flash issue in photo?

Thisis a clear case of "What's wrong with this picture?"

The flash was responsible for the inordinate light falloff.

The flash is also responsible for the featureless disappointing whites, the area where the eye is drawn to first.

The short lens focal length and choice of vantage point were responsible for the distracting foreground plate and other image distortion.

The wrinkled blue cloth looks sloppy rather than flat and the layout looks crowded and lacking a design sense and elegance.

The screaming orange vase is a considerable distraction. Wrongvase. Wrong choice of flowers.

The objects on the plates lack a sense of symmetry and attention to detail.

I don't think this is the subliminal message the client wants to convey.

I apologize if all this seems harsh but for professional results, perhaps it would be more useful to consider Photoshop as a application for image enhancement rather than image salvage.

In this case, don't use the photograph.

Gradients can be helpful in reducing contrast. A black gradient set to Soft Light at maybe 25% will darken the lighter parts of the foreground and reduce the spotlight effect. You can also use a white gradient to lighten the top in the same way.

Hi

You would be better starting with the raw files where you can possible extract more detail in the white plates , but below I took your jpeg image and warmed the foreground slightly in the camera raw filter. Then on a duplicate layer darkened the background and added a vignette, painting in some shadows on a layer set to multiply. The Hue and sat layer is just there to control the reds slightly

Dave