I found this support forum post but the solution provided doesn’t work.
Edit (thanks to @moreeni@lemm.ee for the Stack Exchange link):
Solution - Go to Settings -> Home -> Enable Shortcuts -> Go to a new tab -> Google will be pinned by default, hover over the Google icon -> Click on the 3 dots menu -> Unpin
Go into Settings. Under Search, remove all search engines except the one you want to use. They can always be restored later.