My phone number used for two step verification has changed and I didn't do it, so what happened?

[__ByteCode__]

I got such an email on Oct 11,2020

Hi XXX,
Recently, you made changes to your Adobe security profile.
Here’s what changed:
You changed your security phone number. Your new number is: +447595386873.

The problem is I've enabled two step verification,I didn't change the phone number and that number +44 7595386873 is not mine. The phone number is the key part of two step verification,yet it was changed directly and so easily, how could this happen?   

 Has adobe.com been hacked and all the passwords of Adobe Creative Cloud customers been leaked?

I've waited 12 days and still got no reply, so I've to come to the community for help.

[John T Smith]

1st, Log-in to your account and click this link to make changes https://account.adobe.com/

2nd, This is a public forum, you need the link to Adobe support, not other users
Be sure to remain signed in with your Adobe ID before accessing the link below
-you must also allow 'cookies' in your web browser for this to work
https://helpx.adobe.com/contact/support.html for chat or https://helpx.adobe.com/contact/phone.html
-click the chat icon at the bottom right of the page to open a chat session
-the chat icon looks like '3 dots inside a circle' at the lower right
-type AGENT into the chat window to connect directly to a person rather than the AI
Do be aware that Adobe's staffing is impacted by the virus, so wait times are long
.
Also: beware of answering anyone who sends you a private message
-click for more information about scammers https://tinyurl.com/10791730

[__ByteCode__]

1.>1st, Log-in to your account and click this link to make changes https://account.adobe.com/

I can make the chanage and that's not what I'm talking about,
the point is The phone number used for two step verification is changed by someone else,
This is quite weird and a dangerous signal,can't you get it?

I think I'd better post it here so that the community, for example,could you imagine that next time you try to sign in and find that you cannot because the verification code has been sent to a unknown phone number? wouldn't you be scared then?

2.>2nd, This is a public forum, you need the link to Adobe support

As I said, I've waited 12 days and still got no reply,
I mean no helpful/meaningful reply from them.
Someone did send me a link like this:

We’ve found these self-help articles if you’d like more information about your issue:

https://helpx.adobe.com/x-productkb/global/about-adobe-authenticator-app.html