Do past chats auto-purge?

Level 3

Noticing all but one chat vanished. Do these auto-purge? If so, how long before they auto delete?

Level 9
I'm not sure what specific post or thread you're reffering to, but in the app or forum?

In short, nope on both counts assuming all is maintained correctly.

To keep organized in app, you can hide chat logs by swiping on them.

Messages from deleted ads (deactivated accounts) and messages from banned users and those whom you've blocked will no longer be visible in your chat logs even those that are hidden.

But, they will still be available to staff reagrdless.

If you see replies or threads being removed in the Forums it's mainly due to staff nuking irrelevant off topic conversation / spam / troll posts, including those that turn hostile or into flame wars.
Level 3

Many of the chat threads have vanished from access (not hidden, no where to be found.) One chat still remains. So not following what traspired as this situation does not fit policy, nor procedure.