Recently we upgraded all the PHP images (moodle-php-apache) to use the odbc18 libraries (previously using odbbc17) and the php-sqlsrv 5.11 driver (previously using older versions).

But we have had to revert those changes because of a couple of problems:

1. With ODBC 18, connections are encrypted by default, so we need a way to disable that encryption or to relax the certificate verifications. That's already fixed for 4.2dev (master) and will be also solved by MDL-77669 in stables. Both moodle-ci-runner and moodle-docker will use those new configuration abilities to solve the problem.
2. Apart from the above, there are some consistent failures (PHPUnit till now) detected with the new libraries / php extension. See for example these runs: link1, link2.

Most of the problems in #2 seem to happen within tests using ADOdb (and not our own drivers), so may be it's a matter of passing the new connection parameters to ADODb.

Because of that, in https://github.com/moodlehq/moodle-php-apache/issues/168 we are reverting those changes until the TWO problems above are fixed and we are safe to upgrade again.

So, this issue is about to investigate problem #2 and ensure that the odbc / php-sqlsrv upgrade won't cause any problem.

Trick: To be able to test the new odbc18 and php-sqlsrv 5.11, we have left the "-buster" variants of the php images using them. Only the "-bullseye" (default in Ci) ones have been reverted.