Google iPhone automatically adds links to other websites when you use the app's browser. This feature, called Page Annotations, highlights certain words on a web page and links them to Google search results.
Google includes links on pages you visit through the Google app's built-in web browser, displaying a panel of Google search results related to the word or phrase.
For site owners, this means they have less control over how their content appears in the Google app. Automatically changing links can be disruptive to site visitors and may cause them to miss important actions or links on the page.
It seems this is Google's way of promoting itself on websites without asking permission from the third party website owner.

This new feature is similar to the Google AdSense ad format. Both features turn text on a website into links that display Google search results for products. The main difference is that with the AdSense format, website owners have to opt in, but with the new Page Annotations feature, it will be applied automatically unless the website opts out.
Some businesses have started suing Google over this feature, so Google may want to make this an optional feature when accessing the web, not the default.