Report that "The proportion of deaths involving COVID-19 has been highest in those aged 75 years and over throughout the pandemic, however, this proportion has been lower since the start of January 2021. This likely reflects the impact of vaccinations."
The stats I can find are here - https://www.england.nhs.uk/statistics/statistical-work-areas...
AFAICT they don't give a lot to work with, thought the 18-54 crowd do now make a large proportion of hospital intake than earlier in the pandemic.
The ONS - https://www.ons.gov.uk/peoplepopulationandcommunity/healthan...
Report that "The proportion of deaths involving COVID-19 has been highest in those aged 75 years and over throughout the pandemic, however, this proportion has been lower since the start of January 2021. This likely reflects the impact of vaccinations."
And we have the independent reporting that hospitalisations are now mostly among the under-45 and unvaccinated groups, and that as a result there is less pressure on the intensive wards - https://www.independent.co.uk/news/health/covid-hospital-adm...
So I would say the claim that "most people getting into hospitals now with severe Covid are young and unvaccinated" is probably overstated.