User Agent: Mozilla/5.0 (Windows NT 6.3; Win64; x64; rv:66.0) Gecko/20100101 Firefox/66.0
Steps to reproduce:
Sometime in the past I removed "Google" (and many others) from the list of search engines in the search options, and changed the default search engine.
Today I opened Firefox, and clicked the "New tab" button, which opened the start page.
There was an unexpected "@google" item pinned at the beginning of the top sites list, which I do not recall putting there. Clicking it appears to search Google even though Google is not a search engine in my browser.
Firefox should not be showing Google anywhere after it was removed.