I was setting up the Yahoo Mail app on a family members new Galaxy Tab A8 tablet and found Yahoo requires these domains to work properly on their Android app. I am using NextDNS on my Edgerouter. Blocking these two domains will result in a “Something went wrong” error message after clicking the sign-in button.

udc.yahoo.com
geo.yahoo.com

The next domain causes the same error message, but only when using Account keys to sign in by approving the login from another device.
pr.comet.yahoo.com