Everything is fine in Chrome, it seems to me that this is a problem with Edge.

Not an issue in Edge or in Firefox logged out using Windows 10. I would guess this is some sort of gadget conflict.

I turned on the safe mode before making the screenshot, does that disable gadgets?
Fix: I have Windows 11, sorry for giving controversial info in the start post.

If I disable safe mode, here's my gadget list status:

This is highly peculiar 🤔. I created a new account with exactly those gadgets and loaded it in Edge on Windows 11 and the table of contents shows for me without problem so this is very strange:

The table of contents does seem to be present in that page for you in the sticky header . What happens when you click this icon (to the left of the title)?

Could you also inspect the DOM by the title and send a screenshot as close to this as possible?

I wonder if the table of contents has been collapsed to the heading, but for some reason the icon is not displaying...

Ooops... when I clicked the menu button, the TOC appeared on the left column!!! I probably look stupid now, but I just never noticed that button :-D ! Not it looks exactly like on your screenshot! Case closed :-D Sorry for disturbing.

But maybe there are people like me who just look at that empty white space angrily and... and... try to cope with it.

Just a last question...

I didn't notice the button at the header because I was confident that the left column had expanded already. I thought so because I had it displayed on every Wikipedia article.

Was that a feature? Left column settings are kept somewhere separately for different namespaces?

The table of contents will collapse to the header if you click the "hide" button.

it will then persist across page views.

It behaves the same on all namespaces.

Guys, I see no TOC on the Russian rule about nomination for deletion using Edge for Windows 11. Can you reproduce and confirm?

@Nikolay_Komarov that's because NOTOC used in Википедия:К удалению/Шапка is included. It's not specific to any particular skin.

thanks for a quick clarification!