I have had the same issue with my Spider 2.2.
It’s due to the change in SD SPI speed from 4M to 400K.
I made a comment here - Bug: spi_flash.py not working on BTT boards with SD_SPI_SPEED = 400000
Changed SD_SPI_SPEED = 4000000 in the spi_flash.py and was able to flash via the flash-sdcard script.