Multi-repo makes integrations harder, because you find out about breakages later -- which means that it might be harder to identify the cause and more likely that someone depends on the behavior that broke you by the time you notice it.
But, multi-repo makes local development faster and cheaper -- you're insulated from the churn of everybody else's check-ins. You don't have to constantly refactor everything every time some dependency makes a minor tweak.
You get more done and have a smoother development lifecycle -- but you're going to keep falling behind your dependencies unless you invest in keeping up -- and that part of the process is more unfun the less often you do it.
I currently live in a monorepo. I don't love it. But I've also not loved the multi-repos I've lived in, so... shrug