Can you change maill to number of mobile phone in this update When some user wanna upload project to steam workshop, you need do this steps (example) he must connect his mobile phone number to steam account:

1-select file what you wanna upload
2-steam will open new window where you need set code from your mobile phone. On this stage steam send CODE to owner, or steam make a robot call and say code to owner and item will start uploading when owner set this code in this new window.
For example my account get hacked and bot (haker) wanna post this free arcana in my workshop profile page, and in this stage steam start call me to my number+380********* so i will look into my phone and just decline this random call. And item will not be uploaded even if i get hacked. If i have 5-6 this random calls then steam account must be freezed (blocked) and somehow give me info that there was 5-6 unsuccessfully attempts to my phone number about that my account have hight chance to be hacked by scammer, so i just change passwords mail etc(example)

With this update hacked accounts cant upload items to workshop, because they not have mobile phone of the owner and this scammers will not make more hacked accounts. It will stopped.
Your update have weaknes side.
every hacker scammer site hav special window, where you need set steam loging, set steam password, set mail, set mail password etc, so hacker will know everything if you set info there and you will be hacked 100 percent if you are young guy and don't know what is going on and motivated to get free arcana etc, you will give this info to scammer.
PS even if you give phone number on this hacker scammer site what he can do when steam send code to mobile device before upload items to workshop and this device always near owner.