Upgrade from J3 to J4
Unfortunately there is no way to automatically upgrade from Joomla 3 to Joomla 4.
This is because a lot of changes are made. For example the static extra and price fields are now Joomla custom fields, we implement the Joomla native categories structure, Joomla's multilingual system, frontend editing and a lot more.
When you upgrade:
1) You first need to Uninstall Price List version 3.x component and plugins.
2) Then upgrade your website to Joomla 4.
3) When the upgrade is ready you can Install Price List component version 4.x
4) Add your categories and items and choose your settings.