1. Geo data - someone else in your conversation was searching for fountain pens. Anyone in the proximity could also be getting those ads. 2. Inception - you ma

1. Geo data - someone else in your conversation was searching for fountain pens. Anyone in the proximity could also be getting those ads. 2. Inception - you may have been getting ads/content about fountain pens before the conversation and not noticed it until the conversation. Perhaps the topic entered your mind inorganically. I can assure you the same phenomenon has happened to me even when camping in the woods without phones. Even if these platforms were sneaking enormous quantities of voice data over carrier networks without anyone noticing, 5 minutes of interacting with a voice assistant should put to bed any worry that they would be able to extract useful information from a long string of muffled audio.