virtualbox.org

Hello, I am also facing the same issue with the virtual box 6.1 I am able to install the RedHat 8.5 on it but it did not start the os there. I am also attaching the logs from my VM. Hope this issue will be resolved soon.

Hyper-V is enabled. See HMR3Init: Attempting fall back to NEM (Hyper-V is active).

If your RedHat is not text-only, you might also try more video RAM, maybe 32 or 64MB.