hello, first things first, thanks for the feedback!!
the way the datapack works is that if you have an efficiency 5 netherite tool and haste 2, you're automatically given haste 7, which was the haste level i found that allowed you to instamine deepslate but not deepslate ores. so the datapack gives you haste 7 for 2 seconds. the 2 seconds isn't a glitch, it's the way i made it mainly because i don't know how to do it another way lol, the 2 second is just an arbitrary number i felt like was enough so that the haste 10 effect couldn't be abused with for example tree mining, although you can change it very easily by going into the datapack folder (data > instaminer > functions > mine.mcfunction) and change the "3" into whatever number you want, that's how many seconds the effect will be given . and i have no idea how to fix the pickaxe animation, im guessing after haste 3, there is no animation for that mining speed, at least i don't know of it.
hopefully in the future, with more time on my hands, i can improve upon this and fix these issues that hinder the gameplay a little bit.