Hi, and thank you for looking into this.
Using the icon browser application I saw three icons available for Joplin:
Sizes: 32x32 96x96 128x128 24x24 512x512 16x16 48x48 256x256 scalable 72x72
Note that the first and third start wit a lower case j, and the second one starts with a capital J.
Then I modified the joplin.desktop file found in /usr/share/applications. Here is the original file:
Comment=Joplin - a note taking and to-do application with synchronization capabilities for Windows, macOS, Linux, Android and iOS.
All I did was modify the "Icon=" line to point to one of the icons listed above, from running the icon browser. I think I tried all 3 icons. I will repeat that to be sure.
I installed Joplin from the chaotic-AUR. I also tried to install it from the AUR but there were build issues. I tried to sort those out with what I could find but neither solution worked for me.
I wasn't sure exactly what your reply meant, but I did find an executable called @joplin-desktop:
I modified the "Exec=" line of joplin.desktop to point at this and it didn't make a difference.
I also uninstalled and reinstalled Joplin as some other threads suggested when having icon issues.
If it is not found in DE selected icons theme, the standard icon will be used.
I'm not sure how do check this, but if you tell me, I will.
Thanks again. Any help is appreciated.