At a couple startups, I've promoted a mantra of "everything goes into GitLab".

If some information is not in GitLab Git and CI, it should be in GitLab Issues or (ugly) GitLab Wiki.

Those 4 words avoid a lot of problems. Including avoiding a proliferation of silo'd and leaked and lost information in numerous different SaaSes, apps/programs, and storage services that people will tend to do by default.