Collaborative tags missing, no export/import

How to use GitHub

• Please use the 👍 reaction to show that you are affected by the same issue.
• Please don't comment if you have no relevant information to add. It's just extra noise for everyone subscribed to this issue.
• Subscribe to receive notifications on status change and new comments.

Steps to reproduce

1.export user (old System)
2.import user (new System)

Expected behaviour

Collaborative tags should be exported from the old system and imported into the new system

Actual behaviour

The collaborative tags are not exported/imported, all other is fine.
A simple text search in the export file yields no matches for the tag names. (I don't know if the tags are visible there as plain text.)
I tested admin users and normal users, with the same result.

Server configuration

Database old: Maria
Database new: PostgreSQL

Nextcloud version: (export) Nextcloud Hub 10 (31.0.5)
Nextcloud version: (import) Nextcloud Hub 10 (31.0.5) (AIO)

The issue names no files or tests; start by tracing the user export and import flows for collaborative tags, using the Maria-to-PostgreSQL reproduction described. Verify whether tag data is included in the export, then confirm that an exported user imported into a new instance retains the collaborative tags.