The bug
In creative mode, if the player breaking block using sword/trident (which the block won't break) while moving (walking/running/jumping/falling/flying/swimming), the player will slowed/stopped for a while which cause the movement not smooth. It cause movement speed decreased, jump height reduced, falling delayed and distance traveled shorten.
How to reproduce
Hold sword/trident
Left-click continuously at block while moving
→ ❌ Spike stop effect/ movement not smooth
The same thing happens in 1.14.4 as well . . .