We have found the BRAVE browser is injecting CSS lookup code at the beginning of most render or page pulls.
We have tested 4 browsers on three completely different computer builds. All exhibit the same behavior ONLY with the brave browser.
Tested on Windows 10 1909, Windows 10 20H2, Windows 10 21H1, Windows Server 2016 and Windows Server 2016
Using latest BRAVE browser Version 1.24.86 Chromium: 90.0.4430.212 (Official Build) (64-bit)
Fresh installs, no extensions installed.
An easy way to reproduce - simply open a website in BRAVE and run Lighthouse Speed test report.
Part of the additional page request will normally show in a list of lookups which should be removed to improve performance.
You can also confirm the outbound requests with WIRESHARK.
Example, using the brave community forum page: