https://de.wikipedia.org/w/index.php?title=Aachen&diff=prev&oldid=172175215&visualdiff=1&diffmode=visual starts with the real diff. But then follow some blocks that are all unexpected:
- Headline "Einzelnachweise" (grayed out)
- Complete block of references, multiple columns (not grayed out, but without any change)
- Some navigation templates (grayed out)
- An (automatically generated?) headline "Referenzierungen" (grayed out)
- Partial list of references, one column, numbers differ by 1 from the block above (some grayed out)
(page scaled down to fit most of the diff in one screenshot)
Since the changed text doesn't contain a reference, nothing has changed for them, neither their content, nor the numbering, so they shouldn't be shown in the diff, and neither the headlines (1) nor the templates (3), which are probably only included for context.
The difference by 1 in the numbers for the two lists could be related to T52896: VisualEditor: Support editing citations defined within a template (the first template in the article contains one reference).