Yahoo Japan have decided to make it mandatory to set Japanese mobile phone number when posting comments (press release) after mid-November in order to make the comments section more secure and to improve the health of the discourse space in the comments section. Here are the details of this initiative.
Yahoo! JAPAN is promoting the shift from password authentication to password-less authentication (SMS authentication, biometric authentication) to improve user safety and convenience, and currently requires the setting of a mobile phone number when acquiring a new Yahoo! The introduction of this system in the comments section is part of measures to improve user safety and convenience, as well as to strengthen the prevention of inappropriate comments.
Source: https://news.yahoo.co.jp/newshack/information/comment_SMSauth_20221018.html
https://www.reddit.com/r/japan/comments/y6ypit/mandatory_setting_of_mobile_phone_number_for/