Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/Silicon Labs/EFR32BG22C222F352GN32/CMU_NS/EUART0CLKCTRL#0x0
CLKSEL=DISABLED
No Description
Clock Select
0 (DISABLED): UART is not clocked
1 (EM01GRPACLK): EM01GRPACLK is clocking UART
2 (EM23GRPACLK): EM23GRPACLK is clocking UART
https://github.com/cmsis-svd/cmsis-svd-data