Changed Firefox icon for 2nd installation of Firefox does not stay changed

I have two installations of Firefox on a desktop and a laptop. The first installation is pinned to the Windows toolbar and the 2nd installation has a shortcut pinned to Windows Start. When I saw that the latest update of Firefox to 154 allowed changing icons, I changed the 2nd installation to a different Firefox icon (mini-fox with black background) so it was easy to see which installation to use when both were open. The problem is the changed icon for the shortcut is wrong after shutting down the computers. I do not recall having this problem with the 1st installation or on my 2nd laptop where I only have one installation of Firefox. I suspect this is just a glitch that will likely be fixed in a future update, but it is annoying to have to go through the process of changing the icon every time I startup a computer. If anyone has found a solution for this, I would very much appreciate your help.