Template editor will be automatically opted in for classic themes. This means that users can create custom templates from the block editor. Templates created that way become available for Products. We want to restrict this feature because it currently works differently in themes which explicitly support WooCommerce and themes that don't and because currently we don't have enough WooCommerce Blocks so product page templates can be created successfully.

To reproduce
Requisites:

• WP 5.8 or Gutenberg plugin enabled.
• A classic theme.

Steps:

1. Go to create a new page, in the sidebar, create a new template:
   
   
2. Make some edits and click on Publish. Make sure the template you created is marked for publishing:
   
   
3. Now, go to edit a product.
4. Notice there is a new panel in the sidebar that lets you change the template and select the one you just created.
   
   

We would like the options in this panel not to be available when creating or editing products. So it would not possible to change the template of products.

@vedanshujain we would like to get this included in WC 5.5.0 given that it's the version that will need to support WP 5.8. I added it to the 5.5.0 milestone, but let me know if you have a different opinion. 🙂