Around Oct 27th 2024 Thunderbird stopped downloading my email via POP3.
Found article on Avast about saving cert from Geek:Area and loading into Thunderbird.
I did that, but noticed that cert file is same one I already have in Thunderbird and it expired on that date.
If I disable Mail Shield email download works fine.
For now I instead used Geek:Area and disabled SSL under Mail Shield section until Avast provides new cert.