Thank you for your answer, I am aware about adding "-" before the domain name, I am sorry should have mentioned it in my post 😔. But it does not seem feasible to do that everytime for multiple sites so I'm more interested in setting up a default list of websites I can block.

Thank you, I'll check it out.

Thank you very much, this seems to do the job.

I am sorry but I don't understand how I can setup the default?

I'm a normie who uses firefox because it's the default in my Fedora machine. On windows I just use edge. While on my Android phone, I use it because I like having extensions.