If someone will be able to fix that thing in Blender or at least compile model with no problems, please let me know.

For now I'll just use SMD I guess.

Maybe I shouldn't crop those screenshots in a first place tbh.

First 2 pics are from HLMV, I just cropped them. Looks bad in SFM too, just in case. https://imgur.com/a/xi29rbK

I have a feeling tho that it's the compiler causes the issue. However same thing happened when friend used TF2 StudioMDL instead of SFM one, when I used the one from GMOD and with Cra0kalo Compiler

Sure.
mega nz/#!Pc5HySwR!GbXBTi_mIU_pZXa86rUA-V8Mt6OiMwmdt_moJFohQTA

Straight to the problem:

Here is wing model exported from Blender 2.79b (I think, latest one from Steam for sure) as SMD: https://i.imgur.com/bZE8ifU.png

And here is that same model exported as DMX: https://i.imgur.com/qn5a6cF.png

Both models looks almost identical when loaded back into Blender (except triangles on SMD ofc). However when I decompile model with crowbar and load SMDs I got from it, working wing (SMD) looks like this: https://i.imgur.com/PCGONpI.png while broken wing (DMX) looks like this: https://i.imgur.com/7yxQGrB.png .

Any ideas how to fix it? Problem appears only in model after compiling, DMXs and SMDs exported from Blender are completely fine.

QC file, just to be sure: