Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/STMicroelectronics/STM32F301/ADC/OFR3#0x0
ADC offset register3
Data offset 3 for the channel programmed into bits OFFSET3_CH
Channel selection for the Data offset 3
Offset y Enable
https://github.com/cmsis-svd/cmsis-svd-data