Oh, I was staring right at it in the issue list 
I guess I was looking for something more recent as I guess I assumed something like this would have been fixed during the beta. In the linked OhMyREPL issue, there appears to be a workaround in the meantime by simply prepending using Pkg: Pkg to startup.jl. As for the reason this happens, it’s suggested that it’s because Pkg.jl has been moved out of the system image as of v1.11.
Hopefully this post will serve for future seekers. Thanks!