When bypass capacitors removed circuit still performing?

When bypass capacitors are removed and transmission line is open and RF is coming out with only 3 dB isolation. Following image shows what i am trying to say. Can somebody comment how it's possible. Is it because of coupling?
f=3 Ghz
Circuit is on a PCB substrate and pcb is lightly tightened on the base of a flat heat sink.
Another thing is when i press different poins on the pcb etched are the response changes at the output by 2 --6 dB.

This is the parasitic capacitance between the two open ends.

stray capacitance effect cause this problem if there is no good isolation

Did you see the bottom of the gap? Does it have copper?
You can simulate it in HFSS.
And the grounded difference caused different attenuations.