The sudden disappearance of Slack channels is definitely a thing, along with giant sets of trouble tickets. Don't forget the disappearing wikis... Can't have documentation.
It's definitely given me the opinion that the only reliable docs are what's in git.
Links to stories are useless
Links to tickets are better
Links to wikis are awful
Comments are misleading
Code review links are ok, but mostly link to unreliable sources, and older code review links are gone.
Commit history also goes missing, so don't bother leaving too much info in the commit text
Current code is mostly reliable, but might need extra knowledge to actually reason about.
It's crazy how much useful info get deleted or not migrated or gets moved in a way where you'd never find it again, or the search tools stop indexing it
Links to stories are useless
Links to tickets are better
Links to wikis are awful
Comments are misleading
Code review links are ok, but mostly link to unreliable sources, and older code review links are gone.
Commit history also goes missing, so don't bother leaving too much info in the commit text
Current code is mostly reliable, but might need extra knowledge to actually reason about.
It's crazy how much useful info get deleted or not migrated or gets moved in a way where you'd never find it again, or the search tools stop indexing it