I allow myself to contact you because we lost two items following the update of Woocommerce 4.0.
These are the general search bar at the top of the site and the sidebars built with the HTML block that we had in our product pages.
We configure our sidebar per product page from the “SIDEBAR OPTIONS” tab by selecting the hmtl block.
Have you made the site backup before updating? We always recommend to de before any considerable changes? It is strange, updating Woocommerce never influence or reset the widgets. Please try to restore the site from the backup.