FYI according to
\examples\Test and diagnostics\Read_User_Setup
GPIO 21 is assigned to backlight… but i think GPIO 21 is SD Chip Select on XIAO ESP32S3
this may cause a confilct… i think Backlight is controled on XIAO Round Display by dip switch to pin 0
Its very confusing on ESP32S3 the chip pins and physical pins are different and sometime only 1 number different