When using the USB-to-UART virtual serial port on the Thingy:91 X, the Zephyr console output can become garbled.
This may be an issue with the Connectivity Bridge firmware on the nRF53.
See this issue in Nordic DevZone: https://devzone.nordicsemi.com/f/nordic-q-a/123049/garbled-uart-console-output-on-thingy-91-x