If you go to ThatOneTomahawk's channel, you can see that when he breaks blocks his hand/item moves MUCH faster than usual but still breaks at the same speed. It just looks a lot nicer, and I have his resource pack too!
Howcome blocks break faster in minecraft?
Goh_Dreams
I haven't watched his videos, but it sounds like he has a 'corrupt' mining fatigue status effect, which makes his arm moves significantly faster but he mines at normal speed, if he is using optifine then you might not be seeing the potion particles (you also won't see it if he disabled particles in video settings)
Hope this helped!
Bob
Maybe he is in creative mode
or he has a mod that makes him break blocks faster
Alijah ethan