Essentially, stop showing its own products in a different way than standard results. Stop showing a map from Google Maps when searching for an address. Stop inserting a box of reviews from Google Hotel Finder when searching for "Hotel in London". Stop showing results from Google Flights when searching for "flight from LA to SF". Stop displaying results from Google Shopping with pictures.
Go back to displaying 15 blue links and ads and nothing else. Otherwise, they are unfairly displaying their products in a nicer way than those of competitors, which are only displayed as typical search results.
It would be arguably worse for the user; but it is precisely because the current situation makes it so convenient for the user to click on a Google product that the competitors are complaining. The day Google started displaying unit conversions when searching for "10 miles in km", a dozen websites lost 90% of their traffic. Just because Google answered right away the question of the user.