Here at work we have a very large, very intensive data load that disables and rebuilds indexes as part of the process. We recently added compression to many of the tables and indexes in the database because it was growing quite large (around 28TB at the time). After adding compression, we got the database size down to somewhere around 17TB.
So you can imagine our surprise when the DB size jumped back up to over 30TB after the last data load! In trying to figure out what happened I discovered that most of the data compression was gone.
That’s…not great. Eric shows us a demo as well and notes that it still applies to SQL Server 2019. I’d be apt to call it a bug, myself.