I can read the chip identifier: 74HC165. The HC in 74HC165 stands for High Speed CMOS.
Your assertion is not supported by reality.
Let's review.
Pins 3, 4, 5 and 6 on the 74HC165 IC are inputs.
Pins 3, 4, 5 and 6 on the 74HC165 IC are not connected to anything.
Therefore pins 3, 4, 5 and 6 are floating.
CMOS inputs should never be left floating. Doing so invites all manner of problems. As mentioned in the datasheet for the IC:
(1) All unused inputs of the device must be held at VCC or GND to ensure proper device operation. Refer to the TI application report, Implications of Slow or Floating CMOS Inputs, literature number SCBA004.
And with that I will wish you good luck with your project and say good-bye.