I think the poor search experience, since Cassini was introduced back in 2013 or so,  was the beginning of the current dissatisfaction with eBay.

The only thing eBay appears to have done to ameliorate it has been the introduction of "item specifics", and after making sellers jump though hoops to comply with new rules and regulations, they completely failed to educate buyers on IS. It is still pretty simple to find what you want on eBay IF you know how to use item specifics, but few buyers do.

I reckon just about every change they have made since then has been to attempt to claw back some of the lost business (number of sales/listings and profit) suffered since this disastrous new search engine was brought in.