This plugin works with multisite WordPress installations but requires additional configuration.
For multisite instances, the home
option must be set for each subsite that uses this plugin. Set it at "Network Admin > Sites > [Subsite] > Settings > Home". Alternatively, use WP-CLI to target each site:
wp --url="https://my-wp-backend.example.com/site1/" option update home "https://my-decoupled-frontend.example.com"
Or define a WP_{$blog_id}_HOME
constant for each site, e.g.:
define( 'WP_2_HOME', 'https://my-decoupled-frontend.example.com' );