The entirety of Ninjago's timeline is wrong?

Recently, i had literally nothing better to do, so i decided to rewatch ninjago. But i noticed something off. Im not sure if im correct, but in Ninjago: Masters of Spinjitzu : S02E06, Garmadon went back in time to stop the ninja from meeting. But the ninja stop him and destroy the "mega weapon". Because of this, they returned to the present and Lloyd has no memory of the mega weapon, implying that it never existed in the timeline they returned to. But wouldnt this be incorrect? If Garmadon...