I just went through the previous express entry rounds and noted that the last FST draw was for 500 candidates. If they followed the same quantity this draw as well, that means the actual FSW ITAs issued this time was only 3400. This is less than the usual 3600 ITAs issued in the last few draws, so the shortfall of 200 ITAs contributed to the rise in score. Else, the score would have been 461 or 462 in this draw.
If the next draw is again 3900 with only FSW, we could see a drop of few points for sure