Ah yes, apparently one of the frames in the new GFL Anime, Dolls' Frontline was drawn quite poorly, resulting in this cursed looking M4, and became a meme within the whole Girls' Frontline community.

SFM version:
https://steamcommunity.com/sharedfiles/filedetails/?id=2738903508

The model was ported from a L4D2 mod with permission granted:
https://steamcommunity.com/sharedfiles/filedetails/?id=2735077175

Includes:
l4d2_mod\m82a1\gfl\gfl_anime_ymfm_m4a1.mdl
l4d2_mod\m82a1\gfl\gfl_anime_ymfm_m4a1_foregrip.mdl
l4d2_mod\m82a1\gfl\gfl_anime_ymfm_m4a1_mag.mdl
l4d2_mod\m82a1\gfl\gfl_anime_ymfm_m4a1_mag_pull.mdl
l4d2_mod\m82a1\gfl\gfl_anime_ymfm_m4a1_peq.mdl
l4d2_mod\m82a1\gfl\gfl_anime_ymfm_m4a1_sight.mdl
l4d2_mod\m82a1\gfl\gfl_anime_ymfm_m4a1_suppressor.mdl

Credits :
Valve - Left 4 Dead games
MICA Team - Girls' Frontline game.
Asahi Production - Dolls' Frontline, the GFL Anime.
M82A1闇冥 - Original creator of the model and L4D2 mod.
NeoLin - Porting to Gmod and SFM.