Incorrect results bugs:
Incorrect query results from the CONCAT function
Incorrect results from in-memory optimized tables with clustered columnstore indexes (this one’s only got 2016 in the KB, not 2019 – it’s not clear whether 2019 was unaffected, or just not patched)
Incorrect results on linked server queries with aggregates or joins on a remote table with a filtered index
Incorrect results for inserting data into memory-optimized tables and UDFs
More fixes for inlined scalar functions – out of memory errors, access violations, and non-yielding scheduler errors. They didn’t add any new situations where they stop the function from inlining, though, so that’s good.
Incorrect data mask applied for queries with UDFs
Incorrect results between in-memory optimized tables and disk-based tables – no notes on this one, so guessing it’s super-rare or super-embarrassing or both
Other bugs:
If you have columnstore trace flags 876, 11064, and 11068 turned on, you may end up with single-row rowgroups
MERGE statement fails (OMG, they’re finally fixing bugs in the MERGE statement)
Rollback never finishes if there’s an XE session present for sql_transaction events
Severe spinlock contention – this one was also reported in 2019 CU8, so apparently more work has been done
Improves Query Store scalability for ad-hoc workloads
Memory leak when auditing is turned on
There are also a LOT of fixes for Availability Groups and external queries, like Big Data Clusters and querying Oracle.