Google has announced the rollout of collapsible anchor ads for mobile, which will expand visibility and improve ad performance for ads delivered by Google AdSense.
These collapsible anchors initially expand height to catch user attention but can be minimized for a less intrusive experience.
Google will automatically enable the new collapsible feature within the next 30 days unless you opt out.
This news was discovered by Barry Schwartz on Search Engine Roundtable.
Read the official announcement here: New collapsible anchors option.