Looking on the internet deeply has found these results:

in debt to is the most popular phrase on the web.

in debt of 1411,000 results on the web	in debt to 1542,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
It doesn't look like this phrase is very popular! The search could not find any examples on the internet.	I won't be in debt to anyone. I am deeply in debt to him. And I'm in debt to the show. So he was in debt to Burgess. Fifteen working days before each due date the EMI shall give notification thereof to the central bank of the country that is in debt to the European Community. You're in debt to these people. At least 15 calendar days before each due date the ECB shall notify the national central bank of the Member State that is in debt to the European Community. I'm in debt to the credit union... ...for the loan they made me in '67.

in debt of

1411,000 results on the web

in debt to

1542,000 results on the web

More popular!

It doesn't look like this phrase is very popular! The search could not find any examples on the internet.

I won't be in debt to anyone.
I am deeply in debt to him.
And I'm in debt to the show.
So he was in debt to Burgess.
Fifteen working days before each due date the EMI shall give notification thereof to the central bank of the country that is in debt to the European Community.
You're in debt to these people.
At least 15 calendar days before each due date the ECB shall notify the national central bank of the Member State that is in debt to the European Community.
I'm in debt to the credit union... ...for the loan they made me in '67.