A lot of people apparently didn't get notified. The platform regularly lost emails. (Fifteen years of being on it, such problems were not irregular.) Also, they did offer an export tool, but the results were/are incomplete.

I'll add that some group owners/moderators have not even been able to log into their groups. Yahoo was doing something with needing a yahoo email to get in as admin, even when a non-yahoo email was associated with the account. Those people that lost access to their yahoo email account have been totally SOL.

November 1st? That's barely a month ago. The Vogons broadcast to the world what they were doing just before they did it, too.

I was a member of a single Yahoo group, a local recycling cooperative. I got a notification about the shutdown in mid-November and promptly sent a download request (not a full export). It took literally weeks before I was notified that the download was ready.

And how complete was it? Have you checked? You may be disappointed. You might want to check out one of these while you have the chance:

https://github.com/IgnoredAmbience/yahoo-group-archiver

https://github.com/ArchiveTeam/yahoo-group-archiver

They could have put a notice in the footer they always add to the messages.