Chunks were made with different versions, but I wonder if there's any viable approach to figure out the seed & generating version of minecraft and store just deltas.
It was made on 2b2t, the seed is well known: -4172144997902289642. FitMC makes a video where he shows what the original spawn looked like: https://www.youtube.com/watch?v=ksS00MCQPog
I think "storing deltas" based on seed is largely how Minecraft saves the level already, but you could probably strip out a bunch of useless metadata to get it smaller
There are tools to find seed given some obstruct information like cacti height or bedrock patterns, and it's a problem for those trying to find a private spot on anarchy servers like 2B2T.
https://www.youtube.com/watch?v=36q4Ze0kFu8
https://github.com/DaMatrix/SaveSearcher