If the same problem doesn't exist in a monorepo in a different form then your project is not large enough to be in this discussion in the first place.
The reality is, at some point, having repos that are hundreds of GB with hundreds of active PRs also has its own downsides that requires tooling and workflows to combat. Meanwhile, splitting it all up introduces integration problems.
It's definitely pick your poison, though specific requirements and circumstances make specific paths more or less potent.