Google launched lead form extensions in 2019 as a beta and then expanded it more over the years. Heck, they even beta tested a form of lead forms via Google Ads in 2011. In any event, Google just updated the lead forms to trigger when you tap or click on the headline of the ad, as opposed to a sublink or extension link.
Google said "you can now show a lead form when people tap the headline of your Search ad—rather than guiding them to a landing page."
Here is how it looks now:
Here is how it looked like in 2019:
To get started, add a lead form to a Search campaign. Then go to the campaign’s settings and select the option to "Always show the lead form when someone interacts with my ad." After a potential customer submits a lead form, they can choose to visit your site or return to the search results page.
To learn more, check out this help document.
Forum discussion at Twitter.