By all accounts this report is complete garbage. Good summary here: https://www.swanbitcoin.com/fact-check-darpa-funded-report-on-blockchain-centralization
At its core a blockchain is a single database, so in that sense its centralized. But transactions are added and validated by thousands of people who dont even know each other so in that sense its decentralized.
If you're blockchain relies on a company to keep it going and overtime the resources to run it increase forcing more centralisation of hosting and cost, then no its not decentralised, may be distributed but not decentralised
If your Blockchain has a CEO, it is not decentralized