[Google] Amazon listing of our product has suddenly gained #1 search result spot

Our brand has had the #1 spot for years when searching the brand name OR a similar set of words related to it. Unfortunately as of today, that is no longer the case. I’m including the section below about ads just in case it is somehow related.

Recently Amazon started running search texts ads above our brand on Google, bumping us down from the #1 spot. In response I started running brand-specific search text ads to outbid them, and successfully did so. However today I check and all of sudden the organic Amazon listing has gained #1 spots on both searches that have always put us at the top.

Both the Amazon listing AND our website content have not changed recently. I’ve always assumed Google prefers the official brand sites over Amazon’s listings, but maybe that was ignorant of me. I’ve just never seen an organic Amazon listing at #1 when searching an official brand name.

If the content hasn’t changed, what could have led to this abrupt change?