It is over the legally allowed interest rate in Washington. It might be a crime, under the Criminal Profiteering Act, specifically extortionate extension of credit which is a felony. The requirement for conviction under that law is that the following must be true:
(a) The repayment of the extension of credit, or the performance of
any promise given in consideration thereof, would be unenforceable at
the time the extension of credit was made through civil judicial
processes against the debtor in the county in which the debtor, if a
natural person, resided or in every county in which the debtor, if
other than a natural person, was incorporated or qualified to do
business.
(b) The extension of credit was made at a rate of interest in excess
of an annual rate of forty-five percent calculated according to the
actuarial method of allocating payments made on a debt between
principal and interest, pursuant to which a payment is applied first
to the accumulated interest and the balance is applied to the unpaid
principal.
(c) The creditor intended the debtor to believe that failure to comply
with the terms of the extension of credit would be enforced by
extortionate means.
(d) Upon the making of the extension of credit, the total of the
extensions of credit by the creditor to the debtor then outstanding,
including any unpaid interest or similar charges, exceeded one hundred
dollars.
The contract is civilly unenforceable and the interest rate is above the criminal threshold, also the amount is more than $100. The uncertain part in your description is (c), whether the creditor intended you to believe that the agreement would be enforced by extortionate means, which is defined as
the use, or an express or implicit threat of use, of violence or other
criminal means to cause harm to the person, reputation, or property of
any person.
Threatening to sue a person is not an extortionate means, theft or knee-breaking is.
RCW 19.52.030 addresses what happens to such contracts in court. First, "the contract shall be usurious, but shall not, therefore, be void". Second,
the creditor shall only be entitled to the principal, less the amount
of interest accruing thereon at the rate contracted for; and if
interest shall have been paid, the creditor shall only be entitled to
the principal less twice the amount of the interest paid, and less the
amount of all accrued and unpaid interest; and the debtor shall be
entitled to costs and reasonable attorneys' fees plus the amount by
which the amount the debtor has paid under the contract exceeds the
amount to which the creditor is entitled
So there is some financial penalty, but the debtor does not get to walk off with all of the creditor's money.
There does not appear to be any definitive Washington case law deciding whether "not void" mean "is enforceable", therefore since the contract is not void, it might not be "unenforceable".