If the GU10 LEDs are flickering, there are few possible options, the loose connection somewhere as mentioned above.
It is possible that the LEDs are starting to fail if there were cheap electronics in them.
There could be a problem with interference from a higher power appliance switching in and out and causing either sufficient voltage drop to cause a temporary fail, or a frequency overlay that is causing problems with the GU10s
I would expect that LEDs would be more likely to cause problems on a BT / CAT6 cable than the other way around.
Check if it is specific lamps flickering (indicative of loose connection or faulty lamps) or if it is different lights flickering at different times more like from interference, so then check what other items are operating in the warehouse (or possibly next door), particularly motors or high power applications.