If you are getting notifications from TechSearchService, then your Mac is infected with adware. TechSearchService is adware for Mac.
TechSearchService changes setting in your Mac. First, TechSearchService installs a browser extension in your browser. Then, after TechSearchService hijacks your browser, it modifies settings in the browser. For example, it changes the default home page, modifies search results, and displays unwanted pop-ups in your browser.