I have read about similar Bing hijacking incidents from other Google search users, and eventually found the source of my problem. I'll leave it here for anyone who may experience it in the future. At the time that my issue was recurring I had installed six separate Android apps owned by Microsoft. The culprit (again, at that time) turned out to be a default setting in SWIFTKEY under the 'Typing' category that enabled this keyboard app to route ANY search through any engine to Bing's 'Deep Search,' or a feature named similarly. Why locate this unorthodox keyboard setting – selected/enabled by default – in an unrelated category meant for punctuation, indenting and cursor behavior? . . . To deter you from finding & disabling the Bing auto-search, of course!! I'm not certain if the setting for the hidden search-default deception is still located in the SwiftKey app, but if you do find that Bing is hijacking your Google searches, this incident may provide you with a clue for fixing the problem.