As seen all over the place, adding udm=14 to the URL of a Google search makes the result display less crappy (no ads, no AI suggestions to eat rocks or put glue on pizza, …).
The search results themselves of course are not really getting better with this, but at least the search experience is less annoying.

For the Desktop edition of Firefox you will need to use the udm14 extension to add the udm=14 parameter by default to your search bar.
For other browsers it should be enough to modify the settings of the search URL used and add the parameter (something like https://www.google.com/search?q=%s&udm=14).
Or even better, do use an alternative search engine :-)