Yes its not safe, I had very bad experience with this app, it's not the app itself but the people who managing it in the UK, one of them called Grace she ordered an item from me then she asked for refund and I refunded her but she didn't send me back my item, instead she closed my account.
The people who managing this app in the UK are NOT professionals, and one like Grace is truly thief.
For parents do not allow your kids to use that app its NOT safe to give Depop your bank account details or your Paypal details.