Xperia XZ1 Compact
Brave 1.47.175, Chromium 109.0.5414.87
Long time issue, in all Brave versions I had i my device.
Most of the time, the Android system buttons will be black, making them practically invisible on the bottom bar (which is a very dark grey).
If I change Brave style it will temporarily correct the button color to a very light grey (which is the standard is most other apps in my device)