Yeah, it could be a coincidence in case you are having chats about everyday and common subjects, or subjects that you already have searched for in the past.
I also had this experience with facebook, back in the days when I used Android phones with the facebook app installed (prior to 2018).
(1) Talking with my brother and wife about the city-grown children and their familiarity with animals, and the next time I open facebook, it had an article about this exact subject as “suggested for you”.
(2) Taking with my brother for purchasing new trekking shoes and, 2 minutes after that, I got an ad in Google Mail about a near-by shop with good prices for trekking shoes. With no prior “googling” for the shoes.
And many other cases, that drove me to seeking an alternative, and ending up with SailfishOS.
I believe that “fishing” for keywords in conversations (and not recording whole sessions) is happening years now, and this might be the reason why Android phones with Google framework and apps installed always had more battery consumption than the exact same devices flashed with bare and degoogled Android alternatives (like, e.g., lineage).