It's because there's no one to shill Litecoin, that's why the price is tanking.

So it's a so-so performance, no update on the devs, while other altcoins are busy updating and releasing new version. So obviously, investors are not sold on Litecoin right now, they would rather put their money on something that will make it grow, like ADA, Doge and others. So it just followed the altcoin bull run and can't maintain it price.