Yes there is.  It is because Ethernet Cable is made of copper and copper has a resistamce value that is significant enough to cause the voltage and energy (wattage) of power to drop over a distance.  The block diagram below shows the resistance value to be 20Ohm for a cable length of 100 metre. 

     Suppose PSE sends out 0.35A at 44V = 15.4W
     The wattage loss will be 20 x 0.35 x 0.35 = 2.45W
     The PD will receive 12.95W

Therefore, if the PD requires 12.95W for operation and if the cable length is longer, the power required will be insufficient.

The block diagram originates from Korenix Technology Company Ltd of Taiwan.