Graphs using the <graph>-extension only show empty background in mobile view (both in Minerva and Vector). This seems to be limited to the article namespace, they do show in sandboxes and template pages. This is seen in at least svwp, enwp and dewp.
An example from the svwp article [[ https://sv.m.wikipedia.org/wiki/Nordbalt | Nordbalt ]] in mobile view shows
<img width="0" height="0"
: ...:
```
<div class="mw-graph" style="min-width:600px;min-height:400px"><noscript><img class="mw-graph-img" src="/api/rest_v1/page/graph/png/Nordbalt/0/cadd362816f69c5f3d109bc9fe9a43a7120b0061.png"></noscript><img width="0" height="0" class="mw-graph-img image-lazy-loaded" alt="" src="/api/rest_v1/page/graph/png/Nordbalt/0/cadd362816f69c5f3d109bc9fe9a43a7120b0061.png" srcset=""></div>
```