Custom dead keys combinations defined in .XCompose not working in Signal (Linux/Wayland)

[marc456]

Using a supported version?

• I have searched searched open and closed issues for duplicates.
• I am using Signal-Desktop as provided by the Signal team, not a 3rd-party package.

Overall summary

Some common dead keys combinations work in Signal, for instance: ^ e = ê
But in my ~/.XCompose file, I have defined custom dead keys combinations that work everywhere on my Linux installation, but not in Signal.
They were working in Signal previously (I think, with version 7.6).
I just upgraded to Signal 7.74 and they don't work any more.
Were there any recent change related to the input method?
I use Debian / KDE / Wayland.

Steps to reproduce

1. Add this (dummy) combination in ~/.XCompose:
   <dead_circumflex> <p> : "Z" U005A # Test: ^ p = Z

2. Make sure it works in your editor, in a terminal, in your web browser, etc.

3. Open Signal and type ^ p in the chat box

4. See? Unlike everywhere else, you don't get a "Z".

Expected result

In the above (dummy) example, dead circumflex followed by a p should give you a Z.

Actual result

When you type ^, you see a circumflex underlined, and when you then type a p, the circumflex is removed and neither a p, nor a Z is printed on screen.

Screenshots

No response

Signal version

7.74

Operating system

Debian 13.1

Version of Signal on your phone

No response

Link to debug log

No response