Firefox no longer accepts the sign in process to Yahoo Mail. It is for the overlay for some email addresses. I use Cox email, that you took over. When I try to sign in, there is an overlay that appears for "Allow" or "Don't Allow" the sharing of privacy information. Firefox will not go from a webpage that has an inserted second page. So I have to use Safari. But soon you will make that impossible if you refuse connection from an older version of Safari on an older MacOS like Catalina or High Sierra. And I cannot move to newer versions, as my iMacs are older ones. I am retired and cannot efford spending more than $1000 to read spam email and a few personal messages.