When jumping up blocks or being hit by a zoglin, the strider will start floating in the air without any effects.
Linked issues
duplicates 1
Comments 3

this was in a world created in one of the 1.16 snapshots i'm not sure if it has been fixed or not

This was fixed, but not for striders already spawned, see MC-176032.
Was the world created in 1.16 snapshots?