It was not a "kill switch". If you are able to service some military aircraft to such extent that you fly combat missions, you probably can identify any "kill switches" and work around them. Just look at Iran that is still flying the US made F-4s.
What the US is doing with the F-16s in Ukraine is refusing to update the software on a jammer. The pace of technological evolution in the war is so extreme, that these jammers are in danger of becoming obsolete [1]:
> But the Russian air force could sidestep the jamming by reprogramming their radars to operate at slightly different frequencies. Under Biden, the USAF team might’ve kept pace with Russian adaptation by constantly adjusting the AN/ALQ-131s own frequencies. Under Trump, Ukrainian airmen are stuck with pods whose programming may soon be out of date.
What the US is doing with the F-16s in Ukraine is refusing to update the software on a jammer. The pace of technological evolution in the war is so extreme, that these jammers are in danger of becoming obsolete [1]:
[1] https://www.forbes.com/sites/davidaxe/2025/03/07/france-to-t...