Quarto subcaption labels do not extend beyond z

Bug description

Quarto subcaptions do not extend beyond z

Steps to reproduce

---
title: "BugDemo"
format: html
editor: visual
validate-yaml: false
---

## Quarto

```{r}
allNames <- paste0("a",seq(1:40))
```

```{r}
#| label: fig-rawCN
#| layout-ncol: 4
#| fig-cap: Raw copy number profile.
#| fig-subcap: !expr allNames #names(files)
#| message: false
for (i in 1:40) {
  x <- rt(100, df=15)
dx <- dt(x, df=15)
plot(x, dx)
}
```

Expected behavior

Typically after getting to z, one proceeds to "aa","ab","ac" ??

Actual behavior

Weird characters are inserted after z is reached.

Your environment

RStudio 2023.09.0+463
Mac Ventura 13.4

Quarto check output

[✓] Checking versions of quarto binary dependencies...
Pandoc version 3.1.1: OK
Dart Sass version 1.55.0: OK
[✓] Checking versions of quarto dependencies......OK
[✓] Checking Quarto installation......OK
Version: 1.3.433
Path: /Applications/RStudio.app/Contents/Resources/app/quarto/bin

[✓] Checking basic markdown render....OK

[✓] Checking Python 3 installation....OK
Version: 3.11.2
Path: /usr/local/opt/python@3.11/bin/python3.11
Jupyter: (None)

  Jupyter is not available in this Python installation.
  Install with python3 -m pip install jupyter

(-) Checking R installation...........