The CARES Act originally did not protect economic impact payments from garnishment (specifically, back child support), so the first stimulus payment (EIP1) was not protected. However, the second stimulus payment (EIP2) is protected from garnishment.
EIP3 is not protected from garnishment, but some states and financial institutions have chosen to act to protect these payments. Your EIP3 may or may not actually be garnished—it depends on your state and financial institutions involved.
While the Recovery Rebate Credit is protected from paying off back taxes, it can be used to offset debts owed to other government agencies.