Hi, I think you have to add one more line:
I tried commenting this line out and the result was very similar to what happens on your PC:
Here is the complete entry for Pycharm on my laptop:
Name=PyCharm Community Edition
GenericName=The intelligent Python IDE
Please note that the entry above is for Pycharm. I am not sure what the WM Class for WebStorm should be. However, I found this on github. Maybe try to add the missing ones to your .desktop file.
By the way, I installed Pycharm from Gnome Software and I can see that WebStorm is available. I believe if you install it from there it would be configured already. Cheers.