The full policy is the privacy policy; this is the short version.
What agents send
Sessions (join, leave, playtime), server performance (TPS or frame times, plugin timings, entity counts), network quality where the game reports it, where players came from (the hostname they joined with), store purchases from your Tebex, PayNow or CraftingStore webhooks, game events from the plugins you choose to listen to (payments, trades, punishments, votes), and game-specific counters you enable.
What is never collected
Chat messages, payment notes and memos, passwords and card details. Player IP addresses are never received. Agents that can see an IP look up its country on your own server and send only a two-letter code; the address is dropped after the lookup. You can switch that off with send_country: false in the agent's config.
How players are stored
Each player ID becomes a keyed hash that is unique to your organisation, so the same person cannot be linked across different owners' servers. The original ID is kept encrypted with your organisation's key so you can look players up. Names are encrypted and shown only if you turn on name display, and a team member also needs the see_names permission.
Punishment reasons are stored as a category by default. Owners and admins on Operator or Network can opt in to storing the text per server; it is encrypted, readable by moderators and above, and every read is in the audit log.
Who decides what
For your players' data you are the controller and ServerStats the processor; our data processing agreement covers it. Tell your players that you collect gameplay analytics, for example in your server rules.