Im using this code example:
https://github.com/boschsensortec/BMI270-Sensor-API/blob/master/bmi270_examples/fifo_watermark_headerless_mode/fifo_watermark_headerless_mode.c#L67

and i have observed that when a too high fifo readout length is given to bmi2_read_fifo_data(...) it does request the whole length in one read, breaking the limitation limit given in bmi2_dev.read_write_len.