I solved this by removing +roam from the org entry in init.el and adding (package! org-roam) in packages.el. Then run doom upgrade and it should work. I guess the pinned version of org-roam is incompatible with the current org-roam-server.
I would recommend unpinning the org-roam package instead so that you don’t lose some of the extras that get included in the doom setup process. It was mentioned here as well https://github.com/org-roam/org-roam-server/issues/111