Follow these steps to access your Verizon-Yahoo mail with Thunderbird (and other email apps):
After these steps, Thunderbird will be able to access your Verizon-Yahoo mail again! If you have more than one Verizon-Yahoo account, then repeat the procedure for each account.
I think this procedure will also work for Outlook, iPhone/iPad mail, and other email apps, but I have not tested it with anything other than Thunderbird.
The password created using this procedure is only for Thunderbird (or other email app selected in Steps 5-7). If you use the Yahoo app on a phone or tablet, or access webmail on Yahoo.com, your original Yahoo password will still be active on those other devices.
This is basically the procedure given by Yahoo at https://help.yahoo.com/kb/create-password-sln15241.html