I assume hospitals still get paid for treating patients who just happen to have COVID, and it's possible some of this rise is explained by quick transmission of the new variant without actually causing many of the hospitalizations.

If the 20-29 hospitalizations are really mostly among the unvaccinated, then among the unvaccinated you are seeing admission rates that rival the 60-69 group at the last peak. That does not sound plausible, but then again we do not have good controls, or at least we do not have good controls with data transparently and consistently reported. Either way though it does look like 20-29 admissions are up both relative to all admissions by a reasonable amount, and up much more than where they were fairly consistently throughout the previous era.

Could be data is bunk. Could be younger people really are getting serious infections much more than they were before. Could be enhanced disease. But such dramatic enhancement without neat corroborating data from elsewhere seems to me unlikely.