Change 430854 had a related patch set uploaded (by Evad37; owner: Evad37):
[mediawiki/skins/Timeless@master] [WIP/DNM] Better category handling

https://gerrit.wikimedia.org/r/430854

Another option would be to keep the current duplicated-categories approach, and just change the ids in one lot so they aren't duplicated.

Edit: Thinking about it, this sounds like the better option -- do a smaller change first, and the avoiding duplication stuff / using a different approach for small views can be a separate task

Change 431083 had a related patch set uploaded (by Evad37; owner: Evad37):
[mediawiki/skins/Timeless@master] Use standard category output for sidebar categories

https://gerrit.wikimedia.org/r/431083

Change 430854 abandoned by Evad37:
[WIP/DNM] Better category handling

Reason:
Decided to split changes up into separate tasks. See tasks T193921 and T193923.

https://gerrit.wikimedia.org/r/430854

I'm not really sure this is the right approach.

Using the standard category output works when it's at the bottom of the page because that's what that was generally designed for (and what users populated the categories in the first place for), but for the sidebar it's just... too much, in a lot of cases. We need better category sorting to prioritise ones that are likely to be relevant/useful because showing them all is too overwhelming in that layout.

There is the slight issue that I never actually finished making the sorting/prioritisation for the sidebar (actually I'm not sure I even started?), but that's a better argument for just removing the sidebar categories entirely for the time being and leaving the standard categories at the bottom of the page as matches more expected cross-skin behaviour.

Change 431083 abandoned by Evad37:
Use standard category output for sidebar categories

Reason:
Per Isarra's comments on T193921

https://gerrit.wikimedia.org/r/431083