How much is a Sync fee?

Excuse me, could you please clarify what exactly a "Sync fee" refers to in the context of cryptocurrency or finance? Is it a fee associated with synchronizing data between different platforms or wallets? Or is it a specific type of transaction fee levied by a particular cryptocurrency exchange or service? If it's the latter, could you specify which platform or service you're referring to? Additionally, could you provide an estimate of the amount of this fee, or is it variable depending on factors such as the transaction size or the current market conditions? Thank you for your time.