No. It was no general change of the arcitecture but only from some packages. That is totally normal and depends on the package and maintainer to decrease overall complexity of package building.
You have Nvidia hardware and that pulls in two additional packages (openSUSE-repos-Tumbleweed and openSUSE-repos-Tumbleweed-NVIDIA) which setup a managed repo service. As you already added several external repos, the post installation script of the repo service was not able to prevent a duplication of the standard repos.
You may have a look into this thread which contains some informations regarding the managed repo service packages.