Your front sight is loose, pivoting around the front sight pin? Not sure I follow. Mine has been installed tight and there is no play at all.
The front sight block, #46 in this diagram, is only attached to the gun as a barrel nut that can't be tightened down due to the way it fits into the slide. The guide rod prevents it from spinning completely, but it can still move by probably 20 degrees each way when out of battery.
https://www.czub.cz/zbrojovka/cz-spare-parts/cz75_TS_Czechmate_r_en.pdf
small dab of blue loctite will stop that