Vírus that slows down the copying of files to USB

I'm Being attacked by a virus that slows down the copying of files to USB. File copying starts at a rate of 30MB/sec and progressively slow down to 0 before the copy is completed. I'm using Ubuntu 20.04.

This seems to be some kind of Trojan because the antivirus didn't detect it. I believe he just corrupted the usb driver somehow.

Can anyone help on how to fix this?