Nope, there are no other browser extensions. Just Chromium with uMatrix.

Here's the complete request/response data in HAR format: https://gist.github.com/hrj/f538ed3e67636c94934e221efe67b323

(Note that the UA string is being spoofed by uMatrix, but I don't think that's relevant. I tried disabling the UA spoofing with the same result.)