Display name ignored, name suffix always added on Android

[ygoe]

I have a strage problem here. My CardDAV database is Baikal, hosted on my domain. I'm managing all contacts with the CardBook extension for Thunderbird. So for some contacts, I've added a name suffix that contains old names or other details that may be useful. Normally I want to see them after the name. But when not, I've overwritten the display name with the simple form.

This works fine in Thunderbird and Roundcube webmail. But on Android and there also in the Signal messenger app, the display names always contain the name suffix where entered. I'm also using the Google contacts app (but not storing any contacts in the Google account, I just find the app's UI the least annoying). There the suffixes are also displayed.

Is it Davx5 that introduces the wrong display names here? I find the Android data system very convoluted and obscure, nobody really knows what data is stored where and the poor user never gets to see the raw source data. So I cannot investigate what happens between Davx5 and the contacts app or other apps that use the phone's contacts.

As part of an effort to fix it, I even recreated the server profile in Davx5, and now all starred contacts are missing (the group still exists, but the Google contacts app doesn't show any starred contacts anymore) and some contacts also lost their photos on the phone. I have the impression that Davx5 alters the data in some unexpected way here.

[rfc2822]

DAVx5 (or better vcard4android) uses the FN as display name:

https://github.com/bitfireAT/vcard4android/blob/1b42c582496a297010e9bd428553e5f2d43690a7/lib/src/main/kotlin/at/bitfire/vcard4android/ContactReader.kt#L171-L172

and the displayName is inserted into the content provider, see https://github.com/bitfireAT/vcard4android/blob/main/lib/src/main/kotlin/at/bitfire/vcard4android/contactrow/StructuredNameBuilder.kt

However Android sometimes modifies the name fields according to some rules.

Can you provide a vCard and exact steps to reproduce the problem?