I no longer vape, but when I did it wasn't too hard to find sellers who would provide lab results or other certification that they did not use diacetyl in their flavorings.
Your link also distinguishes between the two:
vape-related injury concerning a teenage boy in Canada has recently gained the media’s attention as well. The 17-year-old boy vaped “intensively,” adding THC to his devices. He initially showed symptoms aligning with bronchiolitis (lung condition normally caused by a bacterial or viral infection), but many patients that have vape-related illnesses in the United States have experienced damage to the alveoli; this type of injury was not found. Instead, his case aligned more with an injury called “popcorn lung,” an ailment most commonly seen in factory workers of microwave popcorn plants nearly 20 years ago. This new vape-related case calls for further exploration into the toxicity of vape liquid, as the patient’s condition could have been caused by the THC added to the vaping devices, or the chemical that affected factory workers in the past - diacetyl. Diacetyl is present in many e-cigarette flavors [14]. The American Lung Association has called for the FDA to require that diacetyl and other hazardous chemicals be removed from e-cigarette cartridges.