I exchanged Bitcoin for Litecoin using CHAIN Mode to save money. The exchange was quick, taking less than 30 minutes.

But there is a problem, I indicated the amount of 0.0019 BTC in the exchange, but sent an amount slightly more than 0.00199957 BTC and received litecoins in the amount, as if I had exchanged 0.0019 BTC.
I thought that this amount of litecoins would be recalculated after receiving the transaction.
Have you factored the fees in your calculations? I understand the fees could make the amount received slightly less than what you sent, you can check the fees yourself to verify, but if that is not the case, then it might be that the automatic recalculation that was announced as shown below may not have been fully implemented. Perhaps their representative here will have answers for you since he is very active on this forum.
📢 Update
We have implemented automatic recalculation
for exchange amounts.
If you send more than the amount
specified in your order —
the exchange will automatically recalculate
and process the full amount you sent
at the same rate.
No need to send the exact amount.
No need to contact support.
Everything is handled automatically.