Why on a site on GOOGLE CHROME I get a MALWARE warning ?

I believe some browsers use the Google provided warnings and some do not. Firefox development was funded by Google which may explain why that browser also shows Google warnings.

Any browser searching for will see the message:

"This site may harm your computer." in the Google search results.

But only browsers with the warning check enabled will get the Attach Site warning screen. The Google report on the site is fairly detailed:

https://safebrowsing.google.com/safebrowsing/diagn...

My Firefox security preferences has a "block reported attach site" option that may be turned off.

It might be an ad problem. Some of my completely legitimate sites received the warning temporarily when one of their advertisers sold slots to an ad agency that loaded their ads with malware.

You get warnings because the site is full of misinformation. Not necessarily malware.