I've been trying to tame tracking from services like Facebook. I installed many ad blockers and tracker blockers on all of my browser, I don't install FB app on my phone, but I still install Instagram app and WhatsApp.
Something creepy (but totally expected) just happened to me. I haven't really been in contact with a friend of mine for quite some time, and we finally chatted again using WhatsApp. Not long after that I opened Instagram, and her photo was the first one I saw haha. It's funny because I don't think I've seen any photos from her in quite some time before this on my IG feed.
Might just be a coincidence, but with all discussion about how creepy they're trying to make their platform as sticky as possible, I wouldn't be surprised if IG's feed algorithm do take into account your correspondence on WhatsApp as well (I live in a country where everyone uses WhatsApp).