That is not necessarily true in the case of the database due to how the drivers work. This would need to be tested in court. It's unclear by the license terms alone.
> 13. Remote Network Interaction; Use with the GNU General Public License.
> Notwithstanding any other provision of this License, if you modify the Program, your modified version must prominently offer all users interacting with it remotely through a computer network (if your version supports such interaction) an opportunity to receive the Corresponding Source of your version by providing access to the Corresponding Source from a network server at no charge, through some standard or customary means of facilitating copying of software. This Corresponding Source shall include the Corresponding Source for any work covered by version 3 of the GNU General Public License that is incorporated pursuant to the following paragraph.
> Notwithstanding any other provision of this License, you have permission to link or combine any covered work with a work licensed under version 3 of the GNU General Public License into a single combined work, and to convey the resulting work. The terms of this License will continue to apply to the part which is the covered work, but the work with which it is combined will remain governed by version 3 of the GNU General Public License.
Users interacting with the modified program over the network have a right to access the modified source, there's absolutely nothing about the client software (database drivers, web browsers, etc) accessing it being considered part of a combined work. You can access a AGPL licensed database or whatever from a proprietary application with absolutely no issue, you just can't modify the AGPL'ed work, expose it to users other than yourself, and not share your modifications.
Do yourself a favor, grab https://www.gnu.org/licenses/gpl-3.0.txt and https://www.gnu.org/licenses/agpl-3.0.txt and run `diff` on them, this is literally the only substantive difference in the entire license text.
No, but there is a definition of corresponding source which includes code beyond the direct scope of the AGPL in case of mongodb: "Corresponding Source includes interface definition files associated with source files for the work, and the source code for shared libraries and dynamically linked subprograms that the work is specifically designed to require, such as by intimate data communication or control flow between those subprograms and other parts of the work."
This is one point of contention that was brought up by multiple people in the past because it puts client libraries into the scope.
Literally the only delta between the GPL and AGPL is the Remote Network Interaction section, it doesn't extend the reach of the GPL license in regards to database drivers, etc.