Please do not spread this site saying it does not submit data to Google. It does guaranteed for the ads, and knowing the search engine scene a bit I would also bet that they submit your IP and useragent to Google for every search query.
It seems recently everybody accepts those claims about privacy protecting search engines without checking anything.
However, startpage's help pages claim not to pass on IP addresses, useragents, cookies, or other identifying information. This claimed-independent report says so too: https://www.european-privacy-seal.eu/awarded-seals/de-110022... — verifying such statements is hard; believe what you will.
I agree, it seems clicking on the Google ads (rather than search results) does put a request via google.com/aclk. Privacy conscious users could block ads to avoid such mistakes. Of course startpage must send some data to google: the search terms are needed to get the search results themselves (as well as for selecting the ads). That could be a privacy leak, for example if simultaneously searching for a name and a sensitive topic. It doesn't seem nearly as bad as tying the search terms to a unique identifier across searches however.