Timestamp, epoc time, and console.log

After some testing I've realize that epoch time from Date.now() and returned from setWatch() are different, and yes it is documented that 2nd one is using float.

I wanted to see in human readable format, and i can do for the result of Date.now(), ie:

console.log("now "+Date.now());
//1677093816456.81469726562
var keyDate = new Date(Date.now());    
console.log("converted Date.now",keyDate);   
//Wed Feb 22 2023 20:23:36 GMT+0100     OK

But I have problems with console.log when using the float from setWatch()

setWatch( function(btnx) {
    console.log("time "+btnx.time);
    //1677093816.43038654327
    console.log("time *1000 "+btnx.time*1000);
    //1677093816430.38647460937        
    var pressDate = new Date(btnx.time*1000);
    console.log("pressDate "+pressDate);
    //1677093816430.38647460937    WHY???
  }
  ,BTN1, {repeat:true, edge:'falling'}
);

On the other hand, from the IDE console, when i assign the previous float*1000 to a var I can see a human readable value, i.e

 var miDate = new Date(1677093816.43038654327*1000);
    //Feb 22 2023 20:23:36 GMT+0100  OK

    console.log("miDate "+miDate);
    // 1677093816430.38647460937   WHY????  

I am sure that there is an easy explanation and my issue is causes from the lack of theoretical basics.