Privacy Mode Leaks Thumbnail to Normal Mode!

Description of the issue:
In certain situations, your thumbnails / preview of the screen in privacy mode is then displayed after you have left privacy mode.

In Mobile, if your main thumbnails have gone to ‘white’ mode (I guess because the cache is old). And you then open privacy mode tabs to the same positions - (I don’t think it does it if the preview is already there).

How can this issue be reproduced?

  1. Have tabs open in the normal view - have them open for so long they’re white rathter then containing a preview (cache timeout I guess?)
  2. Open privacy mode, open some tabs. Look at some stuff you want to be private.
  3. Go to ‘thumnail’ mode in private o you see the tabs.
  4. Click on the private mode but at the same time, as the animation is happening, turn the phone off.
  5. Open the phone- you’re now in thumbnail view of ‘normal’ mode, The whited-out thumbnails have the right title, but the preview from your private browsing.

Expected result:
Your private browsing is deleted. and you dont ever see those thumbails again.

Brave Version( check About Brave):
1.18.1 (20.07.06.15)

Mobile Device details
iPhone 7,

Additional Information:
I’m able to reproduce this sequence with some accuracy - Im sorry in these screenshots in the link below: I was using the search for random to show that htey have a different view, but I wasn’t always able to trigger it (i.e. the random number isn’t the same becuase i did to more then one attempt). But I have triggered this four or five times after witnessing it happening for real.

You have to power down (Or I think background by other means?) in quite a short window after clicking close.

Before -s howing the setup with ‘white’ thumbnails

Secret private browsing of things I dont want shared

do the magic, then open and : Secrets on homepage!

Repeating it with another set of tabs: (note I went into the top left between hence its thumbnail recahced).