On a Mac which Bitcoin Core updated a few minutes ago, the the Blocks folder contains 409.55 GB and the Chainstate folder contains 4.57 GB. But...
https://www.blockchain.com/charts/blocks-size shows, as of yesterday, about 360 GB excluding database indexes.
https://ycharts.com/indicators/bitcoin_blockchain_size shows, as of today, about 360 GB.
https://www.statista.com/statistics/647523/worldwide-bitcoin-blockchain-size/ shows, as of Aug. 15 (a week ago) about 351 GB.
The Mac's Blocks folder contains 5,454 files; the Chainstate folder, 2,226 files. The size difference is about 414 - 360 = 54 GB, or about 7.24 MB difference per file (using 1,024 MB per GB). Does that amount of file overhead seem reasonable and thus possibly the explanation?