While I'm glad that they're looking at this, it seems less shocking than at first glance. This looks like 13 percent of those who are currently listed as Covid hospitalisations, were actually there for other reasons. Of the rest, nearly half had not bothered to get a covid-19 PCR test before going to the hospital.
Given that this group is (we know from other sources) quite disproportionately from those who did not get vaccinated, is this surprising at all? They're people who for whatever reason shun interactions with medical procedures until they are in desperate straits.
Now, the 13% who were did not test positive until more than a couple days after admission, that is something that should be investigated. But it wouldn't change the current picture hugely.