Make sure you have sseedit and open up your entire active plugins modlists with it, find seranas id code and search for it in sseedit to highlight it. It will then show records in red on the right side which is a conflict with another plugin whether that plugin is vanilla or modded. It will also show which plugin is overwriting another. The plugin on the right most side of the right panel overwrites anything left of it that's in red.
But on the other hand, this way serana doesn't need her hoodie to avoid most of the harmful sunlight to her skin sooo
For mods affecting npc appearance it would be easier to move another mod that affects serana into a higher load priority because it's likely the appearance mod is overwriting both in the plugins section and in the mod folders section of the textures and meshes due to headmesh generation and ect. So if you have mod 1 and mod 2 loaded in mod organizer 2 for example, and mod 2 makes serana furry and mod 1 is normal looking serana you want mod 1 to be below mod 2 in mod organizer 2 on both the left and right panel so that mod 1 has priority overwriting both.
Alternatively you can delete the serana npc section of mod 2 in sseedit and then delete the associated serana meshes and textures in the mod folders which will have the last few digits of seranas id as the file names.
If you use vortex I have no idea how to use it because I haven't used it before and if you use Nexus mod manager, switch over to mod organizer 2.