Did you let Firefox save a password for this site and you saw this before Firefox auto-filled your login, or did this pop up after you submitted your username and password as an additional security measure?

Until this is all sorted out, you may want to try using Microsoft Edge or another browser for the site.

it was always saved and now that i cleared cache etc now its doing that all the time really ridiculous how this suddenly appeared when i used the sight not too long ago.

I don't know about physical devices, but I know that if I clear cookies, some sites will text me a code I have to enter. After I pass the test, they set a new cookie so they recognize this device going forward. Unless/until that cookie gets erased and the process repeats.

No its all the time I go to login and it shouldnt and its with firefox and i would like it fixed.