Did you use turbo, buck or Bazel? Without monorepo tooling (and the blood, sweat, and tears it takes to hone them for your use cases), you start hitting all kinds of scaling limits in CI.
They had to open a whole epic in order to reduce the memory usage, but I think all that work just let us continue to use GitLab as the number of services we grew increased. They recommended we use something called parent/child pipelines, but it would have been a fairly large rewrite of our logic.