"Hide Brave Rewards" toggle doesn't work after using Private window

[emerick]

@iefremov reported the following:

I've installed fresh beta and it seems "Hide Brave Rewards toggle" is by default on, while the icon is shown

[iefremov]

STR:

1. fresh install
2. open chrome://settings, toggle "Hide Brave Rewards Toggle" -> it hides the rewards icon as expected
3. open an incognito window
4. repeat step (2) -> toggling the switch has no effect
5. close an incognito window
6. repeat step (2) -> toggling the switch has no effect

kazam_xlc4vv0q.movie.mp4

[stephendonner]

Verified PASSED using latest nightly build and the inline testplan.

First, made sure I could reproduce the bug, using

Brave	1.23.53 Chromium: 89.0.4389.105 (Official Build) beta (x86_64)
Revision	14f44e21a9d539cd49c72468a29bfca4fa43f710-refs/branch-heads/4389_90@{#7}
OS	macOS Version 11.2.3 (Build 20D91)

mini screencast

Then, verified, using

Brave	1.24.29 Chromium: 90.0.4430.41 (Official Build) nightly (x86_64)
Revision	e9c92b1eaca8487e212f3f6bc081fdb6d4863759-refs/branch-heads/4430@{#723}
OS	macOS Version 11.2.3 (Build 20D91)