The bug:

After respawning, mining fatigue and haste still have their negative or positive effect on attack cooldown respectively until the player switches to an item with another attack cooldown.

Steps to reproduce:

Make sure the first slot of the hotbar is empty or contains an item with the default attack cooldown (such as a stick)

Run the command: /effect give @s minecraft:mining_fatigue 60 8

Run the command: /kill

Respawn, then click with the left mouse button to attack

Observe the effect of mining fatigue on attack cooldown persist

Put an item with the non-default attack cooldown (such as a stone sword) in the main hand

Observe the attack cooldown return to default