Recently tested trading functions with a secondary account, mainly to verify the process, and didn't invest much—only $5. As a result, during the transaction, I didn't prepare enough Gas fees in advance in the wallet, and during the Swap, I lost more than $4.

At the time, I thought this money was just gone, but then I suddenly remembered there was a customer service option in the order, so I decided to try. Unexpectedly, I received two refunds this morning and afternoon, totaling $15, which actually resulted in a net profit of $10.

This is probably a system bug, or a special compensation for Gas loss. If you've also encountered similar fee losses while testing transactions recently, you might as well try contacting customer service for feedback. You might get some compensation. Anyway, it's free time, and you might even get an unexpected gain.