Others Unity Modding: Track down missing Asset/Sprite/Image

[Mc swagger]

I am doing a mod for Mission Mermaiden and ran into a bug that I was not able to fix. Since I have basically no experience with unity developement (or sprite base game developement in general), I have trouble with finding a solution for this.
First of all my modding set up (which might be crude): I am decompiling and editing the assembly-csharp.dll of the game with

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which works quite good for me. In that way I have only access to the scripts of the game. For asset and image extraction I use

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but I rarely need it for the things I want to mod.
Now to the problem: In one level of the game the mc has a "N" symbol on her belly. This symbol was present in older (unmodded) versions of the game, but is missing in the newest (unmodded) version of the game. The script is identically for both versions, so ther seems to be no bug in the code. In the decompiled assests I was able to find the corresponding image, but I am not sure what went wrong so that the asset/image/sprite (?) does not show in the game.
Since I can only access and alter the script I have trouble tracking down the issue. Can anyone hint me in a direction how to find the issue?
As you can tell I am a Unity noob so I hope i summarised the issue adequately
Thanks in advance
ps:

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