Self-Join Depths Greater Than 1 Not Working

[tobiasiv]

Describe the Bug

The depth parameter for self-joins does not work as expected. It only applies correctly for depths 0 and 1. For example, if you have nested categories up to depth 5, the depth parameter will not fetch beyond the first level of children.

Link to the code that reproduces this issue

https://github.com/tobiasiv/payload-reproduction/tree/self-join-depth

Reproduction Steps

1. Clone the reproduction repo (branch: self-join-depth)
2. Set the env variables
3. pnpm dev
4. Go to collection Categories and open the document Parent
5. Switch to the API Tab
6. Set the depth to 0: You will only see the IDs of the child docs
7. Set the depth to 1: Children at depth 1 will be fully fetched, and you will see only the IDs of the grandchildren docs
8. Set the depth to a number greater than 1: The behavior remains the same as with depth 1

Which area(s) are affected? (Select all that apply)

area: core

Environment Info

Binaries:
  Node: 20.16.0
  npm: N/A
  Yarn: N/A
  pnpm: 9.7.0
Relevant Packages:
  payload: 3.12.0
  next: 15.1.0
  @payloadcms/db-mongodb: 3.12.0
  @payloadcms/db-postgres: 3.12.0
  @payloadcms/email-nodemailer: 3.12.0
  @payloadcms/graphql: 3.12.0
  @payloadcms/next/utilities: 3.12.0
  @payloadcms/payload-cloud: 3.12.0
  @payloadcms/richtext-lexical: 3.12.0
  @payloadcms/ui/shared: 3.12.0
  react: 19.0.0
  react-dom: 19.0.0
Operating System:
  Platform: win32
  Arch: x64
  Version: Windows 11 Home
  Available memory (MB): 16263
  Available CPU cores: 8