[BillyBob]

Don't forget, the Feb 2019 Gmod patch came out with TTT updated as well.  Likely related.  Go test the knife to see if it's broke again too.

Pro tip

The Newton Launcher was broken before this. 

Knife's not broken either, I've still been stabbed in the foot plenty of times since the update came out

Although the newton launcher was not powerful on players, it still pushed them slightly. It DEFINITELY was able to launch props at a speed which can skill a player. 

Now it’s not doing neither.

I beg to differ. Before this update, I saw the launcher not able to push a prop even in the slighest, let alone a person.

For instance, rooftops. I was an inno on top of the "twin towers" and was hit by a newton launcher. I didn't move even a half-inch, then turned around and killed the person with the launcher.

You just answered the problem you're speaking about. The Launcher is designed for it to forcibly launch players with relative ease to falling to their death. Not gonna argue about what update broke it, but it's certainly broken.