Stop weekly password change
I setup 2FA for Yahoo. Since then, I get weekly forced password changes, claiming unusual activity on my account. And I get asked to enable 2FA because "accounts like yours are targeted". Sure enough, Yahoo has forgotten that 2FA is enabled.
(I use a YubiKey with Yubi Authenticator.) There is no reason for this.
If I don't enable 2FA, I still have to change my password. This is painful: I use the web interface, Thunderbird OATH (2 devices) and K-9 mail (another Oath2 device).
Increasing security as I did is not harmful "unusual activity"..
At the very least, TELL ME WHAT THE "UNUSUAL ACTIVITY" is; it it's coming from me, I'll stop (or file a bug report for whatever software is doing it). If not, I can assure you that changing my randomly generated 23 character password weekly will not provide any better security.
Vague "It's probably unusual activity" responses don't help. All they do is encourage me to move on (or change password in some mechanical fashion that doesn't help security but is doable with Android's limited input facilities.

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We will pass this feedback along to our Customer Care team. They handle account and sign in issues. Thanks!