I have very simple preview.js config

import { withBackgrounds } from '@storybook/addon-ondevice-backgrounds';

export const decorators = [withBackgrounds];
export const parameters = {
  layout: 'centered',
  backgrounds: [
    { name: 'plain', value: 'white', default: true },
    { name: 'warm', value: 'hotpink' },
    { name: 'cool', value: 'deepskyblue' }
  ]
};

but components are not centered.

Expected behavior
Components should be centered.

Screenshots

System:
Environment Info:

System:
OS: Linux 5.14 Fedora 34 (Workstation Edition) 34 (Workstation Edition)
CPU: (8) x64 Intel(R) Core(TM) i7-4770K CPU @ 3.50GHz
Binaries:
Node: 16.10.0 - ~/.nvm/versions/node/v16.10.0/bin/node
Yarn: 1.19.0 - ~/.nvm/versions/node/v16.10.0/bin/yarn
npm: 7.24.0 - ~/.nvm/versions/node/v16.10.0/bin/npm
Browsers:
Chrome: 94.0.4606.81
Firefox: 93.0
npmPackages:
@storybook/react-native: ^6.0.1-alpha.6 => 6.0.1-alpha.6