Search ad impressions have never been category relevant. Which is why I never used them after my 10 hour experiment on the first day the feature was available.
There is a test feature I have for the FP treasury that shows up only when I am not signed in. Under each photo in the treasury is a link to supposedly "ximilar items". Except they are not similar. The tag keywords Etsy is using in this test are not the category, sub cat, or what the item is.. Similar items to, say, a vintage ice bucket are not all vintage items, all ice buckets, or something logical -- the similarity does not involve a noun, or name of the item. Instead, Etsy shows you items also tagged with some adjective from their current marketing push list, a mixture of handmade and vintage items tagged with a word like "mod". Or "party". Or "picnic". This is not how I shop.
This is apparently the new form of category being considered for Etsy where adjectives control relevance, not the category or name of the item.