Today Firefox 84.0.2 showed advertisements in the address bar dropdown of a new tab:

Amazon - Gesponsert
eBay - Gesponsert

I use Firefox because it's the only available browser engine that is not based on Google's Chrome, but I am getting fed up with Mozilla's behavior.

You can disable the ads by opening about:config, searching for sponsored and double-clicking on all the results to change their value to false:

• browser.newtabpage.activity-stream.showSponsored
• browser.newtabpage.activity-stream.showSponsoredTopSites
• services.sync.prefs.sync.browser.newtabpage.activity-stream.showSponsored
• services.sync.prefs.sync.browser.newtabpage.activity-stream.showSponsoredTopSites

Other people with this problem:

• Remove Sponsored Link From Address Bar History
• How to disable Sponsored Top Sites in the Firefox web browser