Steps to replicate the issue (include links if applicable):
What happens?:
What should have happened instead?:
The issue is that the regionlist template uses id html attributes to have the "interactive" map open as the "static" one gets toggled off https://en.wikivoyage.org/w/index.php?title=Template:Regionlist&diff=prev&oldid=4073000.
This is how it's documented: https://www.mediawiki.org/wiki/Manual:Collapsible_elements#With_custom_toggle_link
But, since Parsoid overwrites the element IDs, this can't work.
This is actually an issue with the usage of Collapsible Elements, which uses the same toggle to toggle two elements at the same time with the same ID, which is the circumstance under which Parsoid will actually overwrite the element ID. We suggested an edit on the template in https://en.wikivoyage.org/wiki/Wikivoyage:Travellers%27_pub#switch_to_interactive_map_does_not_work.