This is explained by Henrik in these two issue comments:

https://github.com/doomemacs/doomemacs/issues/7368#issuecomment-1713109316

https://github.com/doomemacs/doomemacs/issues/7379#issuecomment-1721756617

Basically do M-x nerd-icons-install-fonts

You have used vim/nvim so consider using doom emacs.

1 yr experience in vim is quite limited though, maybe the first thing you need to know is the pace of learning emacs/vim depends on how fast you can do the iteration of “read doc + practice”

Post the relevant config pls. Also doom has changed default installation recently to meet XDG standard so you could look into that