According to Android docs you can't use .gif format for your launcher icon
Launcher icons should be 32-bit PNGs with an alpha channel for transparency. The finished launcher icon dimensions corresponding to a given generalized screen density are shown in the table below.
See this link for more informations on how to create a proper launcher image.
UPDATE:
In case that you want some more informations on this problem you can give a look at this forum. Spending a little more time on this I found that some people chose to use "dynamic launcher icons" changing the image programatically (details here). I do believe that this won't fix your problem, but this should provide some details on what's happening and maybe some starting point if you have to simulate somehow this behaviour.
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