Bug 441329

SUMMARY
I tried the Marble Maps mobile application on Plasma Mobile on my PinePhone. (The latest I tried is from KDE Gear 21.08.0.) The application defaults to the "Vector OSM" OpenStreetMap vector data renderer (and actually, I do not see any way to switch to another map). Unfortunately, the rendering is broken (as described below) due to mishandling screen scaling.

STEPS TO REPRODUCE
1. Get a PinePhone running Manjaro Plasma Mobile (or I presume this can also be reproduced on any other Plasma Mobile distro).
2. Run Discover and install Marble Maps.
3. Run Marble Maps from the menu.
4. Look at what gets rendered. Also notice how moving around the map does not resolve the issue.

(Note that I was unable to reproduce this on my desktop computer using desktop Marble and manually setting QT_SCALE_FACTOR=2.)

OBSERVED RESULT
The screen scaling factor (which defaults to 2.00× on the PinePhone) appears to be ignored: The map rendering only fills the upper left quarter of the canvas. (And there is no clipping, so larger features can end up drawing into the unused remainder of the canvas.)

EXPECTED RESULT
The map rendering fills the entire canvas, either by being scaled to twice the size, or by just drawing more of the map.

SOFTWARE/OS VERSIONS
Windows: no
macOS: no
Linux/KDE Plasma: Manjaro-ARM (Plasma Mobile edition)
KDE Plasma Version: 5.22.4
KDE Frameworks Version: 5.85.0
Qt Version: 5.15.2

ADDITIONAL INFORMATION
I filed this against the "android" component because this is with the mobile Kirigami Marble Maps app originally developed for Android. But I am running Plasma Mobile, not Android.