The websites you click on from Google often have a bit of invisible Meta code on them. It works like a camera on the page, reporting back to Meta what you looked at. Tracker blockers can cover that camera.
But lots of sites now tell Meta themselves. You look at a pair of shoes, and the store sends Meta a note saying "this person looked at these shoes." Meta matches the note to your account using things like your email or phone number.
That note goes from the store's computers straight to Meta, so a blocker on your phone never gets the chance to stop it.
how does instagram know what i looked up on google?