likely what they are implying is that chargebacks have indirect costs that you can ballpark around $50 per chargeback. So steam would likely take back the $5 revenue from the developer for the $5 chargeback, but the costs of processing the chargeback are absorbed by steam. i do not know if they have a separate chargeback fee they charge developers for it but it wouldnt make sense to as steam is the one validating and processing payments
likely what they are implying is that chargebacks have indirect costs that you can ballpark around $50 per chargeback. So steam would likely take back the $5 revenue from the developer for the $5 chargeback, but the costs of processing the chargeback are absorbed by steam. i do not know if they have a separate chargeback fee they charge developers for it but it wouldnt make sense to as steam is the one validating and processing payments