We have struggles to understand or interprete the 20 bit extension for high resolution mode (FIFO Packet 4). Is it for higher precision (lower noise) of the output data or what is the purpose if the 20 bit extension? And how do we interprete the additional 3 bytes of data?
Please look at section 6.1 for 20 bit expanation.
Please note following from datasheet
When 20-bits data format is used, the only FSR settings that are operational are ±2000dps for gyroscope and ±16g for accelerometer, even if the FSR selection register settings are configured for other FSR values. The corresponding sensitivity scale factor values are 131 LSB/dps for gyroscope and 8192 LSB/g for
accelerometer.