Using Brave brave-0.22.13-1.x86_64 from RPM repository, on an admittedly old version of Fedora (24).
Brave is unhappy when VirtualBox posts a modal dialog, even though the dialog does not have a global grab. (Brave runs in the host OS, not in VirtualBox.)
After a few minutes, parts of Brave windows become black rectangles, and it soon ceases to function. It is usually still possible to close Brave by the menu operation (File -> “Quit Brave”); but sometimes the first Brave process must be killed. Brave operates correctly when restarted.