Your phone's wifi signal can be used to identify your gait (way you walk). Your gait is unique enough that it can be used to identify you. If there is prior video footage of view, it can be matched to that too. Impressive research, scary implications https://nakedsecurity.sophos.com/2019/10/07/wi-fi-signals-let-researchers-id-people-through-walls-from-their-gait/
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