Google rolled out a new set of optional "conversational attributes" for GMC product feeds. They're meant to help products surface in AI Mode as well as enhance traditional search experiences.

> The following conversational attributes are available as part of the Google Merchant Center product data specification:

> • Question and answer `[question_and_answer]`

> • Document link `[document_link]`

> • Related product `[related_product]`

> • Item group title `[item_group_title]`

> • Variant option `[variant_option]`

> • Popularity rank `[popularity_rank]`

> You can add these attributes directly into your existing product data setup by either using a supplemental data source (recommended) or by adding them to your primary data source. You can also use the Merchant API to submit these attributes. Including them won't impact the approval status of your existing products. Use these attributes to convey descriptive information about your products, including variant data.

> Note: If you already submit specific details in the description `[description]`, product highlight `[product_highlight]` or product detail `[product_detail]` attributes, you don't need to duplicate that data again in the conversational attributes.

The documentation also has a table with "how to use" and examples for each attribute, plus a table with an example product and all the attribute values for it.