clang-format original tooling supports nested ".clang-format" files, meaning that if you edit file buried within folders in a project, then the relevant ".clang-format" file to be used for formatting is searched in a negative recursive way (from the innermost folder up to root folder).

This does not work in your plugin. For example if I have 3rd-party code in my project in subfolder (folder "3rd-party/libraries/libraryA/lib.cpp") and custom crafted ".clang-format" file is in the folder "3rd-party", then plugin ignore the settings file and uses root settings file instead.

This makes plugin practically unusuable with bigger projects which include 3rd-party subprojects whose code should be formatted in a different way or even not formatted at all.