Yes, if you have signatory authority over, but no financial interest in, a foreign financial account, you may still be required to file an FBAR (Report of Foreign Bank and Financial Accounts) if the aggregate value of all your foreign financial accounts exceeds $10,000 at any time during the calendar year.
The FBAR filing requirement applies to U.S. citizens, residents, and certain entities with a financial interest in or signature authority over foreign financial accounts. Signature authority refers to the authority to control the disposition of assets held in a foreign financial account, typically through the power to make investment decisions or conduct transactions. One common example of this is when an elderly parent adds their child to their bank account to allow their child to help them with their finances.
Even if you do not have a financial interest in the account, having signature authority over a foreign financial account triggers the FBAR reporting requirement.
Find more about FBAR here: FBAR: Requirements, Deadlines, and How to File