Used to have my user settings grouped, which makes it pretty easy to change and test, especially when testing new themes that involve some more editing, for example predawn.
With one of the later updates - not shure which it was - ST started to sort the json alphabetically when storing, so all grouping is gone, scroll and search it is.
Is there a possibility to disable that behaviour?
Yes put your own settings in
/Packages/ZUser/Preferences.sublime-settings
and let ST manage the settings of
/Packages/User/Preferences.sublime-settings
so file /Packages/User/Preferences.sublime-settings should have only the settings that ST changes automatically.
Please keep in mind that /Packages/User/Preferences.sublime-settings has precedence from /Packages/ZUser/Preferences.sublime-settings