Drupal core's tabledrag.js uses a hard-coded markup for the representation of tabledrag-hande. Because of this, the markup of that handle is not overridable by themes.
Introduce new Drupal.theme callback for the handle.
There are other hard-coded markups in the JavaScript file.
We should consider repairing them as well, maybe in (a) separated issue(s).
Fixed
9.1
Affects the content, performance, or handling of Javascript.
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It's likely this issue predates Contrib.social: some issue and comment data are missing.