One of many possibilities according to this HIlarious WebSite:
The US F-35C fell into the sea due to strong electromagnetic interference?Russian expert: J-16D has this ability, the People's Liberation Army can do it - iNEWS (inf.news)
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However, a third possibility that caused the F-35C fighter to crash soon appeared. This view is that the electronic fighters of the Chinese Air Force use strong electromagnetic interference. The F-35C lost control and crashed while landing....
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The automatic system for F-35C landing is a magic carpet system specially developed by the U.S. Navy in 2015. After an upgrade in 2017, it is said that even if the fighter plane fails, the magic carpet system can also control the F-35C fighter to automatically land on the on the aircraft carrier. Therefore, Russian experts believe that the electronic jamming pod of the J-16D may have attacked the magic carpet system. After the magic carpet system was interfered, it gave wrong flight data. The F-35C flew according to the wrong flight data and hit the aircraft carrier...."