subholders on a credit card

if the primary user of the credit card increases the credit limit, does the debt to total credit ratio increase for the subholder of that credit card?

There is no such thing as a SUBHOLDER.

There are joint cardholders and authorized users.

Any changes in the account (credit limit, utilization %, etc) are reflected on ALL the credit reports, of the primary holder, joint holder, and authorized users.

And if the credit limit gets increased, the ratio of debt owed to credit limit goes DOWN, not up