@leocg thanks for pointing me in right direction 😉
At https://legal.opera.com/privacy/ there is part stating:
Browser Extensions
You can install browser extensions or add-ons, which can be downloaded from the Opera add-ons website. Most of these extensions are developed by third parties and are subject to their own privacy terms. Please carefully review the terms before installing extensions. Please note that, as described in our Terms of Service, the sidebar messaging services (such as WhatsApp, Telegram, Facebook Messenger, etc.) offered within Opera are provided by third parties. These services will not collect any data from you through the side-bar tool unless you specifically sign into them and use them. Opera does not collect any data when you use these services.
That's what I was looking for.
Thanks again