You wouldn't, but making a repo collection into a mono-repo means your mono-deploy needs to be split into a multi-maybe-deploy.

As always, complexity merely moves around when squeezed, and making commits/PRs easier means something else, somewhere else gets less easy.

It is something that can be made better of course, having your CI and CD be a bit smarter and more modular means you can now do selective builds based on what was actually changed, and selective releases based on what you actually want to release (not merely what was in the repo at a commit, or whatever was built).

But all of that needs to be constructed too, just merging some repos into one doesn't do that.