Hello
He had the same problem, in many places I saw that I had to add this StartupWMClass=com-mathworks-util-PostVMInit en /usr/share/applications/matlab.desktop but it did not help me, finally what I did was add that line but different
StartupWMClass=MATLAB R2021a - academic use
take the value from what appears at the top when opening matlab
but one thing was missing to select the correct image of the icon, since generally one finds that they download it from the internet but this generates an error so it is better to choose the one that comes in the download files, since it seems that two icons appear because there are errors in the matlab.desktop that makes it impossible to open from there
Icon=/usr/local/MATLAB/R2021A/bin/glnxa64/cef_resources/matlab_icon.png
Finally I leave the complete matlab.desktop file
#!/usr/bin/env xdg-open
[Desktop Entry]
Type=Application
Icon=/usr/local/MATLAB/R2021A/bin/glnxa64/cef_resources/matlab_icon.png
Name=MATLAB R2021a
Comment=Start MATLAB - The Language of Technical Computing
#Uncomment the following line and comment the line after to
#force matlab to use the 32 bits architecture
#Exec=matlab -arch=glnx86 -desktop
Exec=matlab -desktop
Terminal=false
Categories=Development;
StartupNotify=true
#Uncomment the following line if you've got several matlab icons in the launcher
StartupWMClass=MATLAB R2021a - academic use
