When AVG, or another AV, finds a threat and notifies me that it found
one, a threat riding on Firefox, it never says what url I was accessing
that had the threat, or what tab it was on? It would certainly help to
know.

Is this because I have the free version? It does't list that among the
advantages of the paid version. But it seems unlikely it wouldn't
know.

I have several Firefox windows open and several tabs in each. This
happened whiile I was having dinner but even if I were in front of the
scree, the connection has been "aborted" and I don't think there is any
way for me to tell. I wasn't visiting any new or risky url afaik.

In this case it identifies it as URL:loTBotnet, from
https://vast.doubleverify.com/v3/vast?_media...... It shows it as one
level of severity out of three.