Hi

Do you have an example of a website where this is happening?

This will help me to replicate the issue here and try to find a solution for you.

Yes! Reddit..com I constantly get pop ups asking me if I want to read the current Reddit thread in the browser that I'm using, or on the Reddit app instead. The stupid pop ups seem to happen every time I follow a link to a new Reddit page/thread, including the first thread I read that day.

This is not an issue with Firefox for Android but is that website trying to encourage people to use their mobile app.

Obviously, and then Firefox for Android allows the pop-up with no option to block it. How do we block the pop-ups?

It's not a pop-up. You can ask on reddit, how to block it.