InstaSlate

A very simple datapack that makes you able to insta-mine Deepslate if you have a Netherite pickaxe with Efficiency V and Haste II.

How it works

This pack changes the mining speed of Netherite Pickaxes by adding the following rule to the minecraft:tool component of netherite pickaxes in an item modifier:

{
  "blocks": "minecraft:deepslate",
  "correct_for_drops": true,
  "speed": 38.3
}

This rule only changes the mining speed of Deepslate. The item modifier only gets applied if your pickaxe has Efficiency V and you have Haste II, and gets removed again if the effect runs out. Therefore, there are no side-effects other than being able to insta-mine deepslate.

Uninstalling

You can run /function instaslate:_/uninstall to remove the datapack. This will also remove the speed buff from any online player who might still have it on their pickaxe.