The image on the right is how the settings app look on macOS 12. On macOS 13 (2022) it was changed to look more to the one on the left, with all the sections selectable in a sidebar and a smaller window. Many users have complained about it, saying that it sacrificed function for form and is part of making macOS more like iOS by mindlessly copying phone UIs onto computers which it isn't meant for. I think its alright, not terrible. And it's the norm with settings apps looking like that in Windows, KDE, Gnome, and some other DEs.
I much prefer the one on the right. Sure, it looked a bit less modern but it wasn’t nearly as glitchy as the newer one. I rely on searching for settings and it almost never works; I really don’t know how Apple ever let the new version into macOS.
OP is just talking about layout, not implementations.
Well the layout of the search in the new version also completely fucking sucks since at least in the old layout it would highlight the section you needed to go to.