It is a variation of sethbling's loot table randomizer, see https://www.youtube.com/watch?v=3JEXAZOrykQ, but also partially inspired by dream's video https://www.youtube.com/watch?v=KDlO64GbxIQ
The original code is sethbling's so all credit goes to him, I just tweaked it a bit.
Basically, it swaps out all the loot tables for other loot tables randomly. It alters the amount of drops, aswell as the type and the drop itself of course.
For example, breaking a vine could have the loot of a blacksmith chest in a village, or breaking sand could drop 43 glazed terracotta.
Download the files
Unzip the loot_tables.zip, and make sure the loot_tables folder is in the same folder as the randomize.py
run python randomize.py (or python randomize.py <seed> if you want the randomizer to have a seed)
That will generate a 'random_loot.zip'
Open minecraft 1.14 and create a world
Move the random_loot.zip into the datapack folder
Restart your minecraft world, and it should work
If you have any questions, you can ask me on twitter or instagram, @jurrejelle