Beyond just "renovating", did he actually FLATTEN the subfloor? Grind the high spots and fill the low ones? To 3/16" in 10' flatness? When you have highs and lows the floor will not follow. It will break. Also, too much underlayment cushion breaks the tongue and groove as well.

" they put down an underlayment and a vapor barrier. "

Does this floor manufacturer allow both? As noted above, the floor is required to be flat befroe putting the vinly as well. The vinyl may be flexing and moving if the floor is not flat. If the floor is not flat, no warranty and the click locks will break if the flooring is moving.

That floor is not adhered to the substrate, so it won't feel solid like a floor that's glued down. If it was merely one area, I'd suspect leveling, but if it's all over it may me normal, as you contractor has claimed.

Check the installation instructions from the manufacturer and you can then call and speak to tech support.