Reliability, mostly. Also some strange cases where it would just plain fail (but then work if re-run).

We do use private scoped packages a lot so that might have some bearing on it.

I use private scoped packages (and monorepos, and yarn) too, and have generally had a fine time with it.

Would be interested in specifics of your reliability and failure problems too.

We just started using yarn workspaces and are running into weird issues where our private scoped packages don't always get installed on `yarn install`.

Yarn claims to be deterministic but I still need to `rm -rf node_modules` regularly when I run into weird build errors. It's quite strange.

Well... I don’t use it anymore because frankly, there’s no need.

Is there any chance that you are using npm to install yarn?

I had mistakenly setup our CI to do that at one point and it caused a lot of hard to debug problems.

I was not, but even if I was that speaks to Yarn’s quality imo because they recommend that as an option.