No it's not. From a practical standpoint, I'm not even sure how that could work. You would have to require all browsers to be open source AGPL in order to load a web page served by it. By way of analogy it seems the equivalent of requiring the mouse and keyboard firmware to be licensed the same as the operating system.
A real life example is Instructure, which makes Canvas (which is agpl) but has other proprietary services that interact heavily with it. It's never been a problem
> require all browsers to be open source AGPL in order to load a web page served by it
Don't be silly: a web server is not distributing a web browser, and thus when you visit news.ycombinator.com, they don't have influence over whether you do that via netcat, curl, or Awesome AGPL Browser 1.0
If, however, they used https://git.deuxfleurs.fr/Deuxfleurs/tricot to serve the http request, then AIUI the AGPL entitles you, as a "13. Remote Network Interaction; Use with the GNU General Public License. (https://opensource.org/licenses/AGPL-3.0)", to ask for the source code of tricot and potentially any systems that it subsequently interacts with
I'm certain I'm going to regret posting this, given how hot-button the AGPL is in every one of these threads
A real life example is Instructure, which makes Canvas (which is agpl) but has other proprietary services that interact heavily with it. It's never been a problem
1: https://github.com/instructure/canvas-lms