I am using Brave Version 1.30.89 Chromium: 94.0.4606.81 (Official Build) (x86_64) (https://brave.com/latest/) installed on macOS Big Sur 11.6
I believe this is related to an long standing technical bug present in Chrome.
The Immersive Fullscreen Toolbar function is not working when the chrome flag “Immersive Fullscreen Toolbar” is enabled.
When you hover your mouse cursor at the top of the screen the toolbar should drop down temporarily for you to use and then disappear again when you are finished using it.
However now you get a blank drop down with NO tabs or toolbar at all.
The Chrome community has reports that this has been broken for a couple of years now, so don’t hold your breath waiting for a quick fix for this issue.
When this was working properly and the Chrome flag “Immersive Fullscreen Toolbar” was enabled the toolbar would drop down temporarily to use when you hovered your cursor at the top of the screen, but lately this is not happening and you get a blank toolbar dropping down instead.
I also like using Brave in Fullscreen Mode with all toolbars and tabs hidden and have them only drop down for usage when needed, it’s nice to have that uncluttered appearance with only the webpage content onscreen.