We're running into an issue in SalesForce Classic with regards to the upcoming SameSite cookie updates in Chrome 80. Defaulting all cookies to SameSite=Lax seems to be causing embedded VisualForce pages not to load. The VisualForce page loads fine in Lightning, but not Classic.
 
We use a VisualForce page embedded on Account Pages (added when customizing the account page layout). I even striped the embedded VisualForce code down to the most basic possible (see code below), but it still fails to load. The embedded VisualForce page throws an “login.salesforce.com refused to connect”.
 
It appears to be because cookies from “visual.force.com” are being blocked. Sample VisualForce page:
 
<apex:page standardController="Account">
    Hello World
</apex:page>

Is there anything that can be done to get past this?