According to this web https://web.getmonero.org/2019/02/01/pruning.html
Why only 2/3 of the blockchain data can be pruned? 1/3 of the blockchain cannot be pruned. This pruning is not as efficient as bitcoin because in bitcoin the UTXO set is just 4GB vs full node size of 250GB approx.
".Monero pruned nodes will only prune 7/8 of the pruneable transaction data. A random 1/8 of the data is maintained. This 1/8 will be used to sync with other nodes. Pruned nodes will also hold and share the most recent blocks". How do I relate 7/8 (87.5%) pruneable transactions to 2/3 (66.6%) pruneable blockchain? These numbers do not match. (at least if it stated 80% pruneable transaction and 75% pruneable blockchain I can still accept.) Or the protocol is just too complex for some calculation to be done.
Which component of the transaction is actually pruned? Is it the decoy's signature? The whole intermediary transaction. It's not clear in the website. I hope I don't have to look into the source code to find the answer.