The Teensy 4.1 board has an 8MB W25Q64JV as opposed to the 2MB flash on the Teensy 4.0. This largely doensn't matter for TinyUsb, except when you attempt to access any memory in the flash above the 2MB boundary, when it fails with a hard fault.
This reads HID devices over host and then translates that to ASCII and sends it over CDC device.