Org mode very strange bug... Conflict with another package?

### I confirm that...

- [X] I have searched the [issue tracker](https://github.com/doomemacs/doomemacs/issues), [documentation](https://docs.doomemacs.org), [FAQ](https://docs.doomemacs.org/-/faq), [Discourse](https://discourse.doomemacs.org), and [Google](https://google.com), in case this issue has already been reported/resolved.
- [X] I have read "[How to Debug Issues](https://doomemacs.org/d/how2debug)", and will use it to provide as much information about this issue as possible.
- [X] The issue can be reproduced on the **latest** available commit of Doom.
- [X] The issue can be reproduced on a stable release of Emacs, such as 27, 28, or 29. *(Unstable versions end in .50, .60, or .9x)*

### Expected behavior

Here is the simplest example I could write:
---- main.org
```
* slide 1
2. [@2] Works
3. Also

#+INCLUDE: "./doesnotwork.org"
```

---- doesnotwork.org
```
** Lorem
9. [@9] \small ipsum
10. ipsum
```

Should compile flawlessly

### Current behavior

- If I try to "org-beamer-export-to-pdf" "main.org", I get:
org-do-latex-and-related: Args out of range: 0, 1

- If I remove the \small on line "9." it works.

- If I copy-paste the content of "doesnotwork.org" into "main.org" it works.

- If I run from scratch, it works (thanks to Ihor Radchenko from org's mailing-list)
1. emacs -Q /tmp/main.org
2. M-: (require 'ox-beamer)
3. M-x org-beamer-export-to-pdf

There's probably a conflict in some packages?

### Steps to reproduce

1. Open main.org in DoomEmacs (upgraded today)
2. M-x org-beamer-export-to-pdf
3. Get error : "org-do-latex-and-related: Args out of range: 0, 1"

Is there a (simple) way to test it in DoomEmacs but without all my installed packages?

### System Information

https://pastebin.com/F56QvGtc

Reproduce the export using main.org and doesnotwork.org with org-beamer-export-to-pdf, then compare DoomEmacs with the emacs -Q sequence that requires ox-beamer. The issue is done when the included file exports successfully with the \small line present and the conflict or configuration cause is identified.

Written by the indexing model from the issue text.