To rephrase, it's possible she already had an underlying mitochondrial dysfunction that was not caused by COVID, but then when she caught the virus it triggered

To rephrase, it's possible she already had an underlying mitochondrial dysfunction that was not caused by COVID, but then when she caught the virus it triggered some symptomatic metabolic dysfunction that's persisting even after she cleared the virus. This kind of thing is known to happen in some people with some viral diseases, but it's poorly understood.