Reversing Camera image has lost its clarity on touch screen.

have you cleaned the camera lens?

 

This. In other situations the camera focus might be adjustable in and out, and the lens position might have slipped.

The MFD isn't going to make a picture out of focus or fuzzy, it is a flat screen display and has no "focus" at all, pixels are more or less 1:1 in position with those in the input signal. A bad MFD might make the image dim, or have holes in it, or be mottled though. It might have an image which moves around on the screen (if there is a problem with sync.) If there is static or other "noisy" image, especially if it gets worse when the car vibrates, suspect a problem with the cables. That sort of issue could be in any circuit board too, like from a cracked solder joint, but always start with the cables since they are more exposed to abuse.

 

I usually have to clean (or rather dry) the lens before backing in when it has rained on the drive home.

On time, when that did not clarify the image, I had to gently (hand) polish the lens with some cutting compound followed by some headlight lens polishing cream.

I don't know what happened to necessitate that (and visual inspection of the lens surface did not show anything of significance), but it cleared up the image so it was vastly improved.