Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/Silicon Labs/Series1/EFM32GG12B/EFM32GG12B810F1024GQ100/QSPI0/FLASHRDDATALOWER#0x0
Flash Command Read Data Register (Lower) (STIG)
Read Data Lower
https://github.com/cmsis-svd/cmsis-svd-data