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If (a big 'if'), they're doing their job correctly, they will have recorded the date and time the suspension sign was  erected, and also a list of all cars parked when the suspension commenced.  Your car was legally parked at the time the suspension started.
When did you depart from your address ? Did you check the car just before you left ?

When did you find the leaflet under the windscreen wiper ?

I found the leaflet today under the wind screen wiper . It can be seen in the council PCN pics as well .

The vehicle VRM is : FV15YZA

I was away due to my father being severely unwell as no was there to look after him .

It was a short stay and I will have to go back again soon as a surgery is planned.

I had a similar PCN cancelled because there was no sign when I left the car, so I asked the council when they put the sign up, they recognised they hadn't provided the required notice, and cancelled the PCN. I had made a post on pepipoo, which is now down, so I can't retrieve the details. I don't remember what the minimum notice was.

You said this was in Wandsworth. A quick search shows the minimum required notice there is 72 hours https://www.wandsworth.gov.uk/parking/parking-bays/parking-bay-suspensions/how-we-suspend-parking-bays/

So, if they can prove they respected that, I fear there is nothing you can do.

...A quick search shows the minimum required notice there is 72 hours https://www.wandsworth.gov.uk/parking/parking-bays/parking-bay-suspensions/how-we-suspend-parking-bays/

So, if they can prove they respected that, I fear there is nothing you can do.

Not true. Councils can't just pick any arbitrary time time limit they feel like and make it stick just because it's on their website. If councils could do this, you an bet a few of them would set a 5 minute limit and cash in on every suspension!

Once an adjudicator sees this case, they will decide if the council are being reasonable or not. I think they would be highly unlikely to rule that it's reasonable to expect car drivers to return to their vehicles every 71 hours just in case the council has followed a policy almost nobody will have read, because it means nobody in the borough could safely go on a week's holiday!

Is there any precedent of Wandsworth's 72 hour notice deemed unreasonable?

Are there explicit laws on what a minimum reasonable notice should be, or is it all left to the discretion of the adjudicator?

There is no law. An authority has a duty to act fairly concerning vehicles in a bay when it puts up signage and they may relocate resident cars without penalty.
The tribunal can't use discretion but can determine if a contravention is fair on the basis of whether it is reasonable to penalise someone who could not have known.

The next step in the enforcement process if no payment is received by the council, is they serve a Notice to Owner to the keeper of the vehicle as recorded on the V5C Registration Certificate for the car. Are you the keeper and hold the V5C, and is the address correct in all detail, and the same as when the contravention allegedly occurred ?

You can only register an appeal at London Tribunals after they have rejected formal representations against a Notice to Owner.