This comes from MDLSITE-6045 where it was detected that basic / initial SQL*Server releases are not always suitable to be used by Moodle.

So the idea is to have a custom environmental check, just for sites using SQL*Server that will look for the exact patch level / cumulative update (CU) that the server is using.

Right now, the requirement to implement should be:

• When SQL*Server 2019 is detected, ensure that it's using CU1 or later.

The message should be something like "CU x is required and it's always recommended to run the latest CU available".

Note that this may have some conflict / problem with Azure DB instances and that needs to be taken into consideration. See MDL-72535 for more details.