@xyfdi Both.. We have obviously the built in auditing we can look at to see what actions other moderators have taken.
We also have discourse which is our official public-facing place. We try to discuss all official business, including suspension of users there. This way other users can give their opinions (we try to be quasi-democratic) and so there is a transparent record of the choices we make and why.
We also often send private messages among the mods to discuss anything that should be considered but isnt ready to blast on public.