This is a tricky question because Yahoo Mail does not allow you to hide your phone number. However, there are some steps that can be taken to make it more difficult for someone to get your phone number if they do happen to find it.
The first step is to go into the “Account Settings” and click on “Privacy.” You should then click on “Privacy Settings” and then click on “Personal Information.

Yahoo does not give out phone numbers.
Yahoo does not give out phone numbers.

Yahoo needs your mobile number in order to send you a verification code for your account.

No. You are required to provide a phone number when signing up for an email account.

You can open an email account without a phone number, but it will be difficult to receive messages and notifications without one.

Yahoo is not asking for account verification.

Yahoo is an email provider, so it can be used for sending and receiving emails. Yahoo also has a search engine, which you can use to find information online.

I believe they are checking to see if you are using the same password for other accounts.

It’s not uncommon for people to use their phone numbers as an alternate email address. If you only have one email address, and you lose access to it (e.g., your account gets hacked), then you don’t have a way of accessing any of your messages.