pkg installer error in macOS 12.3: rights in /Library/Application Support

Are there any changes in the rights of the folder /Library/Application Support starting with macOS 12.3? Our application refuses to install, our postinstall script fails to create a folder (and files in it) in /Library/Application Support. Our installer-gui-script specifies auth="Root" and our postinstall script (postflight python) triggers this: os.system('mkdir /Library/Application\ Support/***') I don't find anything about this in the release change log for macOS 12.3. Everything was fine in previous macOS versions. Thanks