Starting Chrome v86, browser cache is going to be partitioned which are going to have interesting consequences.
What does it mean?
Previously, if you would have loaded a file such as js, css from a CDN from a particular site (lets say Facebook) was cached in the browser cache and available to be used from cache even in a different site (lets say Reddit)
But this is changing now, which means that a cache is domain specific. So a CDN file cached from Facebook will be loaded from the cache only if the requesting domain is Facebook.
Why is this being done?
This global cache from browser have been misused to track users. For example, I can setup a server and track which of my users are not requesting the particular resource (which is same as Facebook) and then make a conclusion that those of my users have logged on to Facebook recently.
References: Cross site leak