Does google know the accounts on devices connected to the wifi my device is connected to?

Recently I've received a lot of YouTube recommendations for topics I am not and have never been interested in, however my sister is. Im wondering if youtube is picking up on her account from our shared wifi. I have never signed in on her device and she has never signed in on mine. At first I assumed google was picking up on her audio since she likes to play videos on speaker instead of using headphones, but a lot of …

accounts device devices google privacy wifi