If this is true, it represents a profound shock to my understanding, indicating that the overall capabilities of US stealth aircraft fall far short of the levels touted in publicity.
My takeaway is more holistic. These platforms and their enabling systems are enormously complex and require considerable ongoing investments in logistical support, training, maintenance and upgrades. That there's a lot more to maintaining an effective force than simply building lots of aircraft, ships and munitions is one of the reasons I've been less bullish than many others about China's ability to produce more and more and more of absolutely everything, because the costs of maintaining and supporting that growing force will balloon also. I suspect that the situation we've seen develop in most nations over time, each for slightly different but often related reasons, whereby ships, aircraft, vehicles, etc. are being maintained in service for ever longer periods of time, is actually less than optimal, and that a more rapid turnover of platforms and systems would deliver superior results in terms of capability vs. life-cycle costs.
In China's case, past platforms have been maintained to exhaustion even amidst the rapid induction of new platforms in part because envisioned future force structures have loomed ever larger. At some point, that will no longer be the case, and the emphasis will shift to maximising the potency of the existing force structure within more fixed parameters. With its demand-side economies of scale serviced by a vast manufacturing base and unparalleled numbers of scientists, engineers and technicians, China is probably better placed than any other nation to implement and maintain a high-potency, rapid turnover strategy going forward.
TL;DR: The lesson to be drawn from poor or declining availability is not that e.g. USAF or Boeing are incompetent; the lesson is that you shouldn't be expecting to operate these aircraft for >30yrs in the first place.