<sigh> Okay, so, the last few Cumulative Updates have had known issues around broken remote queries using the generic ODBC connector and errors with contained availability groups, but I couldn’t really care less about those. If you use those features, I give you bombastic side eye anyway.
However, in the last few days, two more known issues have surfaced.
The first problem is that Cumulative Update 4 can give you incorrect query results when all of these are true:
Your index explicitly specifies the sort order, like DESC or ASC (see update below) Your query has a WHERE filter