Device data cant be processed and unexpected Downlinks for SF

Device data cant be processed and unexpected Downlinks for SF

Hi,
one of my device (EA79E055D0365B08) is sending data via GWs( 1000098E and 1000063C) with good reception (RSSI : -77 & -81 respectively) at SF7. But recently (I guess last 3 weeks) I got following email:

Device EA79E055D0365B08: Node uses higher data rate than expected

then when I looked at the message exchange, I saw several MAC messages at Wireless Logger that I could not understand. As a result, I cant receive the Sensor Data