Unwanted Ad as a new tab on start of Brave

[nitrobga]

Description of the issue:

On start of Brave browser, a new unwanted tab appears.
It’s an ad of online betting service that I never used or visited.

Steps to Reproduce (add as many as necessary): 1. 2. 3.

1. Start the PC
2. Brave browser starts on its own (unwanted as well) showing the last session
3. The session is as it was before the last shutdown/restart
4. Immediately a new tab appears right next to the last tab viewed (not always at the end of the tab que) and loads “the https://winbet.bg/bg/casino/all” website.

Actual Result (gifs and screenshots are welcome!):
Unwanted ad as a new tab.

Expected result:
No unwanted tabs.

Reproduces how often:
On start or pc, regardless if brave was closed before that or left open during shutdown.

Operating System and Brave Version(See the About Brave page in the main menu):
Windows 10
64bit
Brave version
Version 1.22.70 Chromium: 89.0.4389.105 (Official Build) (64-bit)

Additional Information:

I visit sites with popup tabs sometimes and Brave manages to get almost all but not all of them.

I ran a virus check, downloaded the latest most expensive Avast antivirus and ran extensive checks of the whole system.

I ran a safety check inside brave.

I ran a Chrome check for unwanted software.

I reset Brave and when the problem persisted - uninstalled and then reinstalled.

The problem persists.

[nitrobga]

Sorry, it was clearly malware.
After trying 3 different programs (Avast Premium, Bitdefender and Malwarebytes) the last one found the little culprits and it seems thigs are getting better. All the symptoms are gone (for now).
I’ll wait a few days before I celebrate and share any developments.
Please let me know if there is a way to share the culprit’s details to some database for future references so I can be helpful to others in the same situation.