I live in a country where very very few people use Netflix, therefore it's very rare to see ads about it, because my country is so tiny, Netflix Just don't target it. My country is outside EU, so companies don't have to respect GDPR or any privacy related law as far as I know.
My friend doesn't have Facebook installed on his PS4. He wanted to try Netflix, I created a profile for him from my account so he could try it. He only installed it on PS4 watched few movies and after 2 days, for the first time ever, he started seeing Netflix ads on Facebook.
He never searched for the keyword "Netflix" or watched a YouTube video about Netflix. If Netflix was the one sharing the data, then I should be the one seeing ads, not him, as far as Netflix knows, it's my account.
He has black tape on his webcam. He only used Netflix for about half an hour just to explore it. His laptop wasn't turned on.
He doesn't have Netflix installed on his phone and never visited their site, I wounder how Facebook knew he was using Netflix