When first introduced, Centered Layout would only be active if there was a single editor (or if there was a horizontal split maybe? I never used that layout, so idk). If, while in the Centered Layout, a "split vertical" command was issued, the centered layout would be disabled until there was only one editor again.
In the most recent release (1.25.0), this behavior was changed such that, rather than disabling the centered layout while there's a vertical split, the editor stays centered with the same dimensions, and the split occurs inside this centered container. There was something in the release notes about how the old behavior was confusing or had unexpected results, but no details on what the actual unexpected behavior was.
I'm having trouble thinking of a situation in which this is ever what you want. For the Centered Layout to be most effective, the width of the editor should be close to the width of the actual text being edited, that way the text is actually centered in your view. When I say "give me another editor next to my current one," I never want two editors that are half the width of the text that I'm editing, but that's how the new centered layout behaves. You'd have to either
If not a full reversion back to the old behavior, can we at least get a configuration option to re-enable it? Obligatory XKCD
Centered:

Split:

(Experimental duplicate detection)
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@jechase thanks for the xkcd, that is one of my favorites.
I would only consider introducing an option if more users ask for this. So for now leaving this open and waiting for feedback.
fyi @joaomoreno
Related to #53694.
I am using only single layout with always enabled and centered zen-mode for a long time. v1.25 just adds some extra gaps around tabs and nothing more for me. Also (according to #53694) the option zenMode.centerLayout has no effect at all, no matter false it or true.
I know Zen-mode isn't in priority for some reasons, but I hope that mode will be changed in near future. And Zen-mode will be really Zen-able, flexible and clean (like in Atom editor, for example).
@isidorn Current centered layout behavior is silly. I have to either resize workspace every time i open a second editor or keep it wide all the time, which defeats the purpose of centered layout.
The core problem is that people (I assume I am not the only one seeing things this way) would like to keep editors' size fixed and expect workspace resize to fit, but current implementation does exactly the opposite.
Is there any consideration about this issue? It feels like there's been a major regression and the current response is simply "wontfix" and "by design".
I have enough faith in the team that I honestly don't think such an oversight was by design.
Yes, we will consider bringing back some of the old behavior in the future.
fyi @joaomoreno
IMHO the centered layout option should remember its position respecting open vertical split editors
So I would not have to resize my centered layout width every time I change the amount of opened splits.
I have introduced a setting workbench.centeredLayoutAutoResize.
This setting behaves in such a way that when enabled it will automatically resize the centered layout view to max width when more than 1 group is open.
I personally like this behavior and have decided that it is enabled by default to true.
So the behavior suggested in the inital comment will now be the default behaivor and users can opt out of this.
You can check this out in next weeks insider build and provide feedback. Thanks
Feedback on setting name, default value and behavior are very welcome
fyi @bpasero
@isidorn will it fix the ~regression~ as-designed feature (#53694) when tabs bar has a reduced size like an editor pane? 馃
@isidorn should this rather be workbench.editor.centeredLayoutAutoResize?
@Ky6uk no, it will not. Sorry
@bpasero yeah, editor prefix makes change looking at other settings whcich have the editor prefix. Updating it...
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@isidorn Current centered layout behavior is silly. I have to either resize workspace every time i open a second editor or keep it wide all the time, which defeats the purpose of centered layout.
The core problem is that people (I assume I am not the only one seeing things this way) would like to keep editors' size fixed and expect workspace resize to fit, but current implementation does exactly the opposite.