The Bug

Normally If you run and hit Player or mob,your sprint will be stopped when he get damage,So it supposed to be because he got damage.
But your sprint will still be disabled if you hit player with gamemode 1 while sprinting.

Attacking entities with a knockback attack disables your sprint.

Please note that in order to perform a knockback attack, you must sprint and attack an entity with a fully charged hit, (no attack/damage cooldown should be occurring when you do this). Please also note that if you were to hold down your sprint key whilst reproducing this, your sprint will stop momentarily before returning to normal after performing a knockback attack.

Steps to Reproduce

• Summon an entity and stand a fair distance away from it.

• /summon minecraft:creeper ~ ~ ~ {NoAI:1b}

• Begin sprinting towards it, attack the entity with a knockback attack, and pay close attention to your sprint as you do this.
• Take note as to whether or not attacking entities with a knockback attack disables your sprint.

Observed Behavior

Attacking entities with a knockback attack disables your sprint.

Expected Behavior

Attacking entities with a knockback attack would not disable your sprint.