In many of the default themes from brave://settings/manageProfile, it’s very difficult to tell which browser tab has focus — the color of the active tab is not different enough from the inactive tabs. This is doubly true when computer’s night-time blue-light filter is active — and even more so if using f.lux to manage eye-strain screen color temperature (f.lux can go more red than system-native blue-light filters).
I don’t know if these theme are inherited from Chromium, but if not, it would be nice if Brave could tweak the active-tab color.