Hi @-sche, thanks for taking the time to report this!
I went to https://en.wiktionary.org/wiki/dove?debug=true#Derived_terms (thanks for the test case!) and can confirm that there is no expand/collapse option on the right (and no output in the web browser's developer tools' console) - this issue can also be seen on the pages for the templates themselves at
For the records, T163974 might be a similar problem (but that report is unclear).
(And on an unrelated note, https://en.wiktionary.org/wiki/MediaWiki:Gadget-purgetab.js is broken (link is undefined). And the styles of the gadgets "Legacy scripts" and "DocTabs" are loaded twice so someone should migrate them to type=general.)
This seems to have been resolved on-wiki with https://en.wiktionary.org/w/index.php?title=MediaWiki:Gadgets-definition&diff=42867887&oldid=42211374. I'm pretty sure the underlying issue is the same as T165031.