Nope. You are not right again. If you looked at the link that I gave above, you would go to the original description of the bug:
https://bugs.chromium.org/p/chromium/issues/detail?id=913964
So, CVE-2019-5787 (Issue 913964 in the repository) is a Chromium bug.
There are patch for the bug:
https://chromium.googlesource.com/chromium/src.git/+/8cbb211d93b114c2bc348837d787aa5c8e545e40

You can check other Chromium security bugs: https://bugs.chromium.org/p/chromium/issues/list?q=type%3Abug-security%20os%3DAndroid%2Cios%2Clinux%2Cmac%2Cwindows&can=1

I do not know by what principle they relate CVE to which vendor.
But as you can see above, the bug is declared and fixed in the chromium.
So brave had this bug too.

By the way, they paid $ 3,000 for this bug.