I want to preface this by saying that yes, I know that Instagram is bad. I am planning to get rid of it in the future but as of now I have to keep it for communication with people who are only on that platform.

So I have grapheneOS, use protonvpn (free version), use mull as my browser, and do not have google play services enabled on my phone. I do have some apps downloaded through aurora store such as Instagram, whatsapp, mychart, and mint mobile, but the rest came from f-droid.

I have noticed multiple times that after having private conversations on matrix, I get Instagram content in my feed that is scarily accurate to the conversation I had on the other platform immediately after. I know that things discussed in Instagram direct messages and group chat will give suggested content based on those conversations, but I get stuff that that is very specific to what I have ONLY discussed on matrix and didn't look up via my browser.

So my question is how is Instagram doing this and what can I do to mitigate the spying it's doing on my other apps. Thanks.