Describe the issue
Steps to reproduce (sadly this might be OS specific):
- Open codemirror.net with Firefox
- Using the ES OS keyboard layout: type "\" (see image)

Notice that this problem does not happen on Chrome nor Safari. It is only present in Firefox.
I tested with two keyboards (ES and US physical layouts) and different OS layouts:
| Keyboard Layout (physical) |
MacOS Layout (software) |
Can render \? |
| ES |
ES |
No |
| ES |
US |
Yes |
| US |
ES |
No |
| US |
US |
Yes |
Additionally, when trying to type "\" it shows the autocomplete pane/window, I made a small gif which might be of help:
https://i.imgur.com/dNhpTtP.gif
Browser and platform
macOS Version 15.2 (24C101), Mozilla Firefox 140.0.2
Reproduction link
No response