Google has announced that future updates will make it more difficult to activate the Assistant by mistake. The company has also taken pains to reassure users that their audio data will not be collected by default in the same release. A specific opt-in determines whether the same will be analysed by humans or not.
https://www.notebookcheck.net/Google-plans-to-make-the-Assistant-s-attention-more-selective-in-the-future.435269.0.html