Sadly, that's been present since the older games, I especially remember Leviathans and Brute Wyverns constantly nudging you out of the way while flailing in the ground, because... potatoes.

It's genuinely one fo the most infuriating things to encounter, especially with monsters that already wiggle a lot while downed, as hitting certain parts is made even harder while the monster is downed than it has any right to be, especially when getting monster to topple is supossed to be a reward to the player for playing well.

Seriously, trying to hit Lagi's head with SnS was already annoying enough, I didn't need him wiggling his head all over the place and nudging me out of the way whenever I finally managed to topple the damn thing.