Great question — answering as the UphillTech team:
You're using "motorized" in the alt text for the butterfly valve and "electric" in the alt text for the ball valve, so Google is picking up on more words relevant to the search at the beginning of the butterfly valve's alt text and deciding it's more relevant. Try wrapping your related products in an <aside> rather than a <div> to make it more clear that it's not part of the main product.
Full answer by Chris Cox: https://wordpress.stackexchange.com/a/426346 (CC BY-SA 4.0).
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