Yes, but only if you have given the app permission to do so. 

When you sign up for a loan app, you will be required to provide your bank account details, which the app will use to disburse loans and collect repayments. 

In most cases, loan apps will ask for your authorization before debiting your account.  

This means that you will have to agree to their terms and conditions, which include allowing them to debit your account when repayment is due.

It is important to note that loan apps are regulated by financial authorities, and they must adhere to strict guidelines when it comes to debit transactions.  

They are required to obtain your authorization before debiting your account, and they must also notify you in advance before doing so. 

Additionally, loan apps are required to provide you with a clear breakdown of all charges and fees associated with the loan, including the interest rate and any penalties for late payment. 

It is also worth mentioning that loan apps cannot debit your account for an amount that exceeds the loan principal, interest, and any applicable fees.