OBS Studio by default uses the Rec 601 standard for colors. Piczel's stream management uses Rec 709 throughout, which means that conversion between these two can cause color discrepancies.
If you would like to have the most accurate colors available to your viewers using our HLS or Streamshots players (RTMP streams are not processed and thus are always accurate to the source) be sure to set your Color settings appropriately in OBS, as shown below.
In the Advanced section of OBS' settings, change your Color Space Setting to 709 and Color Range to Full.