Accompanying Files
Observation Details
Operating the interactive map, the default on page load is an activated accordion item "Mobilfunknetz" in which are three checkboxes (2G, 4G, 5G). It looks like it functions as a "Multiple Selection List". For reference, see BFIT-Bund Handreichung "Accessible design of user interface elements – Multiple Selection List".
When selecting and activating another accordion item, the map's context changes to that item's content, meaning when "Festnetz" item is activated, the Mobilfunknetz content is removed from the map. As the "dropdown" / accordion item itself should not have functionality to change content, but the interactive elements in it should, activating the "dropdown" evokes an unexpected context change. On a page about 5G Mobilfunknetz / Netzausbau, moving to a "Festnetz" map is considered unexpected behaviour.
Remediation Notes
Remediation of this issue might take significant effort. Ideally, the use of more fitting interactive elements helps users to navigate the options in a more predictable way. If "Mobilfunknetz", "Festnetz", and "HotSpot" are exclusive options, using a fitting component, like a singular selection list, a dropdown, or radio button group, would identify the interactive element right away.
There are a few easier ways to remediate but not without potentially "removing" content.
Removing Festnetz & HotSpot options from the map
Announcing change of context to make it an expected change, which then would not be considered a failure; this could be done by giving the accordion item button an accessible name of "Nur Festnetzausbau anzeigen"