In Moodle ≤ 3.11 it was possible to direct link to a section by putting an anchor to the section id in the URL.
That possibility has gone in 4.0 (lost functionality).
It would be required for such links to function again, because with the section-4 link, when a new section is inserted before the link shifts to a different course section.
Linking to 'unmodifiable' course section URLs is important e.g. when you insert hard links in PDF for example. Or imagine a gamified approach when after a completion a link to a section becomes visible and clickable. You don't want to adopt those links all the time when a new section is inserted.

Thanks for taking into consideration.
I hope there's a simple solution which doesn't tick screen readers into reading out too much.

I couldn't find any existing issue but MDL-31842 and MDL-40416 are somehow related to this and might be fixed with this issue.

Reproduction steps:

1. Create a course with some sections.
2. Give section 4 a title "Target".
3. Copy the link to section 4 from the course navigation and add it to a label.
4. Verify clicking on the link jumps to the section "Target".
5. Add a section and move it to position 3 (or anywhere before "Target").
6. Note that clicking on the link does not jump to the section "Target" any more.

Best,
Luca