The Adafruit library is too difficult for me. Anyway it supports QSPI mode and SPI mode. What if you use SPI mode and see if the results are the same?
//Adafruit_FlashTransport_QSPI flashTransport;
SPIClass SPI_2(NRF_SPIM2, PIN_QSPI_IO1, PIN_QSPI_SCK, PIN_QSPI_IO0);
Adafruit_FlashTransport_SPI flashTransport(PIN_QSPI_CS, SPI_2);
Adafruit_SPIFlash flash(&flashTransport);