happened to my world with 25w41a, as well as visual glitches with ominous banners
I'm fairly certain the patch notes describe that as intended.
I've had the same issue with 25w41a, only it happened before I even made a spear, let alone enchanted it. Also my base’s skele horses all unalived on first game launch in the new snapshot.
I'm not getting any knockback with my enchanted spear flat ground or otherwise.