Do you have a source on that? My understanding is it was more transmissible, and suspected to be more severe but there was no hard data.
Also quoted from CDC's FAQ:
> "In two different studies from Canada and Scotland, patients infected with the Delta variant were more likely to be hospitalized than patients infected with Alpha or the original virus that causes COVID-19."
https://www.cdc.gov/coronavirus/2019-ncov/variants/delta-var...
Honestly I wasn’t aware that there was this much uncertainty at the time, I remember hearing that delta was affecting young people in India more strongly way back in early 2021
https://www.ucsf.edu/news/2021/08/421171/how-dangerous-delta...