SUMMARY
The images in the feed page of planet.kde.org don't scale to match the size of the browser view.
https://imgur.com/a/wWDJRv8 

STEPS TO REPRODUCE
1. Open https://planet.kde.org/
2. Click on the link icon (🔗) next to any feed to open a feed page
3. Srink the website width up until an image width is bigger than the width of the brower (or just open it on mobile) 

OBSERVED RESULT
The image overflow and doesn't scale.

EXPECTED RESULT
The image scale and mantain the aspect ratio.

SOFTWARE/OS VERSIONS
Mozilla Firefox for Arch Linux 119.0 (64-bit)
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Operating System: Arch Linux 
KDE Plasma Version: 5.27.9
KDE Frameworks Version: 5.111.0
Qt Version: 5.15.11
Kernel Version: 6.5.9-arch2-1 (64-bit)
Graphics Platform: Wayland

ADDITIONAL INFORMATION
It seem to fix it adding the following css style to the image:
max-width: 100%;  
heigth: auto;