I don’t know all that much about jellyfins runtime on android in general, but if it depends on dotnet could you try running dotnet —info

If that returns nothing or outdated packages, you could probably install or update them with something along the lines of:

pkg update

apt install --reinstall \ dotnet-hostfxr-9.0 \ dotnet-runtime-9.0 \ aspnetcore-runtime-9.0 \ dotnet-host