The U.S. Air Force has increased training for pilots and air crews so they can operate in an environment where many of their electronic devices (GPS, communications, and radar) would be shut down by enemy electronic warfare. Given the growing use of Internet based espionage by the Chinese, as well as their successful use of spies, the air force has to deal with the possibility that China has obtained classified data on American electronics and come up with ways to interfere with the operation of that equipment.
These unpleasant surprises are quite common in the early stages of a war when two nations with different military customs, tactics, training methods, and capabilities clash. It’s common for nations to misinterpret what their potential battlefield opponents are capable of and these misinterpretations do not become clear until the two sides meet in combat. Deficiencies are usually fixed as quickly as possible and modern electronics are built to be easily modified (usually via their software) to adapt to situations like this. But that takes time (days, weeks, months) and in the meantime the aircrew has to adapt.
Russia and China have long had similar training as they always assumed that the Americans would have better electronic warfare tools. That has been the case historically. But the growing realization of the extent of the Chinese espionage effort has caused American military leaders to consider more debilitating “worst case” scenarios.
Some types of interference are expected, like jamming (of comm, radar, or GPS signals), and most air forces do some training to deal with this sort of thing. But what the air force is dealing with here is massive and sustained interference of the kind only possible if the enemy knows the details of how your electronic equipment works.