The newest Cumulative Update for SQL Server 2019 has this gem in the release notes:
It’s not a known issue, it’s an improvement
This is a massive problem if:
You have databases encrypted with TDE You take backups WITH COMPRESSION (which has a history of bugs already), or you have the server’s default compression option turned on You’re doing log shipping to other 2019 servers You patch the primary to CU16 before you patch the secondaries
You might say, “Well, you should always patch the secondaries first” – but in some shops, here’s how they approach patching: