If you have the version from the repository then download the latest version from the download page. You can leave the installed version as is.
Edit the launcher and replace the command line with "<path-to-unzipped-download>/SweetHome3D-Java3D-1_5_2-7.5" (the current version is 7.5). If you create a new launcher then use the SweetHome3DIcon.png in the unzipped folder as an icon.
First try a different desktop and see if the problem persists.
Dodecagon.nl
1300+ 3D models, manuals, and projects
Thank you for your prompt reply.
After many attempts, I've decided to switch to Debian 13.
With Xfce, everything works as expected without any struggle.