I put this down to one of four things:
1. Poor quality content.
2. Users have realised hodling their sats is more valuable because they are expecting some pumpy price action.
3. Novelty has worn off.
4. To 'like' is less accountable
Discussion
I agree that Liking is less accountable. I also tend to Like stuff as a way to let someone know I saw their stuff, kind of like a "someone is reading your stuff, you're not posting into the void", saving zaps for content that I think is worthy of v4v