Just opened the App Store to check. There’s an ad for chrome on the home screen. I click search and before I start typing search suggestions pop up. The first one is for chrome. I type Firefox and click search. The first result is chrome.
At least it's always only one ad, but on the other hand it takes up half the screen. Plus the title is the name of the app, not "Firefox". Really, the bar is not very high for ads
The worst thing about it is that it looks exactly like a regular app listing, too. The only indication that it's an ad is a tiny "ad" icon - a pale blue square with slightly paler blue text. And that icon isn't even next to the (large and visible) app name, it's next to the (small and greyed out) tagline.