The transaction fee is, depending on the blockchain, voluntary. It is paid to the miners, who secure the network and process transactions into new blocks. To incentivise them, to include a transaction earlier you can pay a higher fee.
Bitpanda sets the fees for cryptocurrency withdrawals automatically, so that a transaction is confirmed early but does not overpay. To ensure that, Bitpanda dynamically adjusts the fee depending on the congestion on the network.
In Addition to that we are using different techniques where possible, such as Segregated Witness and transaction batching to further reduce fees for our customers.