Quick navigation bar sorted incorrectly when prefixes are used

Checklist

[X] I can reproduce the bug with the latest version given here.
[X] I made sure that there are no existing issues - open or closed - to which I could contribute my information.
[X] I made sure that there are no existing discussions - open or closed - to which I could contribute my information.
[X] I have read the FAQs inside the app (Menu -> About -> FAQs) and my problem isn't listed.
[X] I have taken the time to fill in all the required details. I understand that the bug report will be dismissed otherwise.
[X] This issue contains only one bug.
[X] I have read and understood the contribution guidelines.

Affected app version

1.3.0

Affected Android/Custom ROM version

Android 14

Affected device model

Motorola Edge 50 Pro

How did you install the app?

Google Play Store

Steps to reproduce the bug

Add a prefix to a contact's name. Go to the Phonebook list. Sort by First name (not Full name).

Expected behavior

The quick navigation bar is sorted correctly and points to first names, not prefixes.

Actual behavior

When you add a prefix to the contact's name and sort the contact list according to the first names, it sorts correctly. However, the first-letter quick navigation bar on the right gets sorted according to the first letter of the full name, including the prefix. This letter then doesn't correspond to the correct part of the list. When you tap on the affected letter, you are taken to the name with the prefix. See attached screenshots.

This doesn't happen in the Contacts app, only in the Phone app.

Screenshots/Screen recordings

Additional information

_No response__

FossifyOrg / Phone