Resolved! Possible wrong FLASH_ACR description in STM32G0 RM
STM32G071RB: According to RM 3.7.1 reset value of FLASH_ACR is 0x00040600, verified on hardware. But the description of indiviual bits doesn't fit.RM: Bit 11 ICRST, Bit 10 reserved (cleared), Bit 9 ICEN, Bit 8 PRFTEN, so cache enabled, prefetch disab...