Hi @Ecnexam.noterbel, thanks for taking the time to report this and welcome to Wikimedia Phabricator!

Please use the bug report form (linked from the top of the task creation page) to create a bug report, and fill in the sections in the template:

What happens?:

What should have happened instead?:

Firstly reported here.

This is working as intended. If you zoom you are letting the browser you know that you can't read the content. If the sidebar did not stack on top this would result in unreadable squished article text which is surely worse.

Could you rephrase this task as a problem? What can't you do because of this behaviour?

@Jdlrobson thank you for answering.
The user explains what is the problem for him (translated with Deepl):

• scrolling is required to access the article (but you have to know this, otherwise you may think the page is empty)
• the text of the interlanguage links T301262 says "On this language version of Wikipedia, the interlanguage links are placed at the top right of the article title. Go to top", while the links are below when in zoom mode.
• when you zoom, by default the ToC doesn't appear, it is "hidden" under a button that you have to click on to make it appear. The function of this button is not at all obvious, you must first notice its presence, and then you must guess that it is used to open/close the ToC
• When you open the ToC, it "cuts into" the article, you can't read it anymore; so it's impossible to have the summary and the article text on the screen simultaneously. In zoom mode, this feature doesn't bring much compared to the previous version where the menu was present at the top, it requires the same number of clicks to navigate between the content and the summary (edit: actually, it's even worse, it requires an extra click). It would be problematic to open the default summary without fixing this cropping problem, especially for users who did not understand that they had to click on the icon to make the summary disappear.

In zoom mode, his suggestion is to have the ToC opened on the top on the sidebar, (more like in the legacy Vector and I think like here).

Probably some points are resolved with T311160.
In my experience, the article is squished with narrow screen as you marked here T306660, however the "squished article" effect is not so effective with 150% of zoom on a standard screen. In my opinion, it should be possible to set the visualisation of 150% as in the 133% for the 1366x768 resolution.