Please set wgCollectionDisableSidebarLink to true for dewiki in InitialiseSettings.php
The sidebar link is already hidden via a Common.css rule since 2021 without objection following the discussions here and here. In order to reduce the amount of community maintained code that is delivered to everyone via Common.css, we would like to use the config option instead, which in this case wouldn't cause any visual and workflow schange for the community as the link is already hidden. See this thread on the German equivalent of IANB.