Accessibility issue: The order of some headings is not coherent (WCAG 2.1 - 1.3.1 Info and Relationships)

Accessibility issue:

The order of some headings is not coherent. Some headings that would be subordinate to other headings in terms of structure and importance have a higher heading level by mistake.

This is especially problematic for blind users, as they picture the structure via the heading and its levels.

Sometimes a heading level is also skipped for no apparent reason (but that's a minor accessibility issue).

Example for this issue:

In the calendar, the heading: "Calendar" has heading level 5, while the heading for the month below has heading level 4, which is a higher heading level, although the month should be subordinated to the heading "Calendar" both in sense and visually.

How to fix the issue:

The heading level of the parent heading should be higher than that of the child heading. In this case, "Calendar" should be heading level 4, while the month should be heading level 5.

Success Criterion:

• WCAG 2.1 - 1.3.1 Info and Relationships 
• EN 301 549 v.3.2.1 (PDF) - 9.1.3.1 Info and relationships