Notable changes:

• mempool clustering is released, and removed the CPFP carveout in previous versions
• RBF validation has been tightened (see https://delvingbitcoin.org/t/an-overview-of-the-cluster-mempool-proposal/393#rbf-can-now-be-made-incentive-compatible-for-miners-11)
• -privatebroadcast added to sendrawtransaction RPC, to broadcast over tor/i2p only
• an asmap has been embedded and can be enabled with -asmap or -asmap=1
• default dbcache has been upped to 1024 on systems with more than 4096MiB of ram

other changes in the linked release notes