suddenly can't retrieve ATT Yahoo emails with Thunderbird after trying every suggestion

Using Thunderbird 115.18.0esr Supernova 64-bit on Mac laptop OS 10.13.6. Worked fine for years, with ongoing Thunderbird updates, even though Mac OS is 32-bit. Suddenly, after 10/6/26 can't retrieve emails although I can see them on the ATT Yahoo server website. Can still send emails with Thunderbird. Inbound server settings are: POP server inbound.att.net, Port 995, SSL/TLS, Normal Password (I long ago created a Secure Mail Key, and even tried creating a new one). But inbound server name doesn't show in Saved Passwords (only outbound server with Secure Mail Key as password)? I have tried everything suggested, repaired my inbox folder, updated Thunderbird files, etc. in Profile as recommended. But still no prompt for password when attempting to get messages. Just shows "Done" at bottom left with no new messages received. But new messages are seen on server website. So it appears that Thunderbird isn't able to connect to the ATT Yahoo server to get emails. Why? And what else can I do? I love Thunderbird and want to continue using it.