The popup ads desktop notification keeps showing non-stop on the bottom right side of the Opera browser window. This article shows you the steps to turn off desktop notifications in Opera browser.
Step 1: Go to Preferences (Mac)/ Settings (Windows).
Step 2: Click Advanced in the left sidebar, and click Privacy & security.
Step 3: Under Privacy and security, click Site Settings.
Step 4: Click Notifications.
Step 5: Toggle off Ask before sending (recommended).
Step 6: Click Basic in the left sidebar.
Step 7: Go to Sidebar section, click on Manage sidebar.
Step 8: Toggle off Enable notification badges for messengers.
Source: Opera Help > Web preferences > Manage desktop notifications