https://www.omim.org/entry/617347
This is the article AMBOSS cites for Type III. They assert type III "is characterized by hyperlipidemia due to accumulation of remnants of the triglyceride (TG)-rich lipoproteins (TGRL), very low density lipoproteins (VLDL), and chylomicrons (CM)." I believe that these changes ensure better clarity around what the research is saying about type III (an accumulation of chylomicrons/VLDL and their remnants) without committing specifically to exclusive elevations in VLDL and chylomicrons. This also helps align the information between AMBOSS, the table provided in the extra section, and information provided by pixorize (IDL is a VLDL remnant, therefore VLDL remnants being elevated is an easier logical jump to understand and make)
Source: AMBOSS - https://next.amboss.com/us/article/4o03XS?q=familial%20dysbetalipoproteinemia#Zcf3f04936e0fb0160f55c4cf97f37d23
Amboss table still says that it's chylomicrons and VLDL that are elevated