Google’s Danny Sullivan has confirmed on Twitter that Google does not change the organic search results for your website if you advertise for a keyword:
We are not removing search results because an ad is showing. There's no test or anything like that. What happens in search results is entirely disconnected from ads. Period.— Danny Sullivan (@dannysullivan) November 13, 2020
URLs sometimes drop from the index temporarily for a variety of reasons, none of which relate to ads.
How to optimize your website for Google’s organic results
The SEO tools in SEOprofiler help you to optimize all pages of your website for high rankings on Google and other search engines: