> The concerns are similar to US supplied fighters.

I doubt that they actually do, just cutting off software support substantially cripples the F-35 in multiple ways and without spares they aren't going to fly very long (on the timescales of fighter programs).

The risk isn't worth the payoff because if anyone found that killswitch, US arms sales would crater.

All that said I don't think my country should be buying US systems if European equivalents or near equivalents exist anyway for geopolitical reasons.