Take Profit and Stop Loss orders can be set to triggered based on Mark or Quoted Prices.
If you set TP/SLs to trigger on Quoted Prices, they will only execute when the Quoted Price you can exit the trade at crosses your trigger.
If you set TP/SLs to trigger on Mark Prices, they will execute at the best available price as soon as the Mark Price crosses your trigger.
On smaller, less liquid markets, Mark Prices and Quoted Prices can differ more significantly due to spread.