I got installed in my Avast Secure Browser an extension called "coupons" without any notice

I understand your concern, but the “Coupons” extension in Avast Secure Browser is legitimate and safe. It’s a feature designed to automatically apply the best coupons when shopping online, helping you save money. It comes from Avast, a trusted cybersecurity company, and isn’t a virus. It doesn’t access your personal or payment information—just applies discounts at checkout.