on current SC 3.3.2 understanding document
https://www.w3.org/WAI/WCAG22/Understanding/labels-or-instructions.html
in examples section last example is :

• A U.S. phone number separates the area code, exchange, and number into three fields. Parentheses surround the area code field, and a dash separates the exchange and number fields. While the punctuation provides visual clues to those familiar with the U.S. telephone number format, the punctuation is not sufficient to label the fields. The single "Phone number" label also cannot label all three fields. To address this, the three fields are grouped in a fieldset with the legend "Phone number". Visual labels for the fields (beyond the punctuation) cannot be provided in the design, so invisible labels are provided with the "title" attribute to each of the three fields. The value of this attribute for the three fields are, respectively, "Area Code", "Exchange", and "Number".

But H65 technique as been removed since 2019 from the list of associated technique in the SC. So this example isn't relevant anymore and must not be considered as a possible solution

In consequence this example need to be removed or changed to something like

• A U.S. phone number separates the area code, exchange, and number into three fields. Parentheses surround the area code field, and a dash separates the exchange and number fields. While the punctuation provides visual clues to those familiar with the U.S. telephone number format, the punctuation is not sufficient to label the fields. The single "Phone number" label also cannot label all three fields. To address this, the three fields are grouped in a fieldset with the legend "Phone number (separated in three inputs respectively Area code, Exchange and Number)" to be compliant with SC 3.3.2 and each individual field must have accessible name to comply with SC 4.1.2