Gantt view does not show card dependencies, although dependencies are set on cards

Steps to reproduce

Create a Deck board
Create multiple cards on the board
Set start date and due date on the cards
Add dependencies using “Add dependent card” in the card details
Open the Gantt view of the board

Expected behaviour
The Gantt view should display the dependency relations between cards, for example as arrows/links between the related tasks.
Actual behaviour
The cards are shown in the Gantt view, but no dependencies are displayed at all.
This is reproducible not only with very short cards, but also with longer cards spanning multiple days.
Environment

Nextcloud version: 34.0.2
Deck version: 1.18.3
Installation method: containerized setup with Podman
Deck app version confirmed via:

php occ app:list

Maintenance / repair already tested:

php occ maintenance:repair

Browser cache was cleared
Result: no change

Additional information

Dependencies are clearly visible in the card details UI
Almost all tested cards have defined dependencies
The issue is therefore not limited to a single broken card or to milestone-like / zero-duration tasks
The problem appears to be either:

dependency data not being passed to the Gantt frontend, or
dependency rendering missing/broken in the Gantt view

What was tested

Short cards
Longer cards with proper start and due dates
Multiple cards with dependencies
Clearing browser cache
Running occ maintenance:repair

In all cases, the Gantt view still showed the cards themselves, but never displayed dependency relations.
Possible direction for investigation
It may be useful to verify:

whether dependency data is included in the API responses used by the Gantt view
whether the Gantt frontend correctly maps Deck card dependencies into dependency links
whether the rendering of dependency arrows/links is currently incomplete or broken

Screenshots
I can provide screenshots showing:

card details with configured dependent cards
Gantt view where the same cards are visible, but dependency links are missing

Start with the Gantt view and the API responses it uses, then compare the dependency data visible in card details with what the frontend receives and maps into dependency links. Reproduce with multiple cards that have start and due dates and configured dependencies; done means the Gantt view displays the corresponding arrows or links between cards.