it's not a blockchain at all. sounds almost like a SQL database. also, certainly not decentralized, but a federated system:
"Unlike previous blockchains, which view the blockchain as a collection of blocks of transactions, the Libra Blockchain is a single data structure that records the history of transactions and states over time."
https://libra.org/en-US/white-paper/#the-libra-blockchain
"Unlike previous blockchains, which view the blockchain as a collection of blocks of transactions, the Libra Blockchain is a single data structure that records the history of transactions and states over time."
https://libra.org/en-US/white-paper/#the-libra-blockchain