On the scale of bad 1-10 where 10 is the absolutely worst case this is a 12 easily.
(Elon’s strategy of blowing up smaller versions of their rockets more or less deliberately doesn’t sound so insane in the light of this.)
SpaceX had a very similar failure during a static fire test in 2016 that destroyed the rocket, payload, and a few key parts of SLC-40 that took them over a year to repair and return to service (September 2016 -> December 2017). The concrete flume trenches were literally melted.
https://spaceflightnow.com/2016/09/01/spacex-rocket-and-isra...
That was a full size rocket on a real mission with the $200M payload on board during the static fire, which is ostensibly worse. The payload was not integrated yet in Blue Origin’s case.
I'd say on a scale of bad 1-10, 9 and 10 are reserved for incidents that cause loss of human life. YMMV.