That’s very unlikely. It’s running UBB Threads, which, from what I can tell, has an auth subsystem, which au minimum would do hashing. If it’s providing you with a default at sign-up, that’s different and is what appears to be a configurable setting.

If it is completely generated for you, here’s what probably happening:

1. User creation module runs a password generator and stores this and the username in memory as string variables.
2. User creation module calls back to storage module to store new user data in db, including the value of the generated password var.
3. Either the storage module or another middleware module hashes the password while preparing to store.
4. Storage module reports success to user creation.
5. User creation module prints the vars to the welcome template and unloads them from memory.

TL;DR as this is running on a long-established commercial php forum package, with DB storage, it is incredibly unlikely that the password is stored in the DB as plaintext. At most it is likely stored in memory during creation. I cannot confirm, however, as it is not FOSS.