Blocked a frame with origin

I’m using a Chrome-derivative: Epic Privacy Browser that as the name suggests is privacy-oriented.

During checkout, I’m getting a rather cryptic and potentially scary to customers error message:

Blocked a frame with origin “https://www.domain.com“ from accessing a cross-origin frame. [screenshot]

(where domain.com is of the same domain the shop belongs to.)

I’ve disabled all privacy features, but the message still shows up.

Haven’t tested if payment goes through, but choosing other non-paypal methods do work.

As more privacy-friendly Chrome-derivatives seem to be proliferating nowadays, think would be a good idea such kind of too technical messages with not a clear remedy nor action to be part of the admin logs, if possible, and not get exposed to customers.