Timezone empty after opening contact in Thunderbird

Describe the bug

Because this is in combination with Thunderbird I'm not sure whether this is a bug for the contacts app or an issue with Thunderbird.

Nevertheless:
If I modify a contact (in Thunderbird), add a Timezone, the TZ field is gone after sync and cannot be created/edited within the contacts app.
After clearing it in Thunderbird, it's available in the contacts app again.

After testing that again, I think it's more of a Thunderbird issue, so I'm going to check their bug report page as well. Maybe someone here already knows of this though.

Steps to reproduce

1. Go to 'contacts app'
2. Click on 'create
3. Open Thunderbird, synchronize contacts.
4. Add TZ to contact from 2. in Thunderbird
5. synchronize
6. Open contact in contacts app again, see that TZ is gone

Expected behavior

Add Timezone in Thunderbird, synchronize contact and see Timezone in contacts app.

Actual behavior

After adding Timezone via Thunderbird, field is gone and cannot be edited/seen/added in contacts app.

Contact version

5.0.3

Operating system

Linux 5.15.0-58-generic x86_64 (docker)

PHP engine version

PHP 8.1

Web server

Apache (supported)

Database

MariaDB

Additional info

User client:

• Linux Mint 21.1 (Vera)
• Firefox 109.0 (64-bit)
• Thunderbird 102.4.2 (64-bit)

Start by reproducing the sync with Contacts 5.0.3 and Thunderbird 102.4.2 using the listed steps, then compare the contact data before and after adding TZ in Thunderbird. Done means the timezone survives synchronization and is visible and editable in the contacts app, while clarifying whether Contacts or Thunderbird is responsible.