Yes, the swing changed in UUBuild29Sep2026 to match the original. Even in the previous build you always had to hold the button before letting go, but that wait wasn't faithful to the original: it used to get shorter as your skills went up. Now it is about 0.7 seconds for everyone and every weapon, and letting go sooner cancels the swing. After that the blow needs to be charged up: a battle axe takes about two seconds to reach full strength, and letting go earlier still swings, just with less force.
The crosshair colour tells you where you are: grey, not ready yet; red, ready at minimum strength; then orange, and flashing green and white at full strength