I have tried to re-upload my skins, and i've specifically chosen the "slim" model but when i join a server/realm all skins including my own have the black lines on the back and are all the classic steve models. I have looked through other bug reports and i have seen that others have had the same issue. This has been the case across other versions (i have tried 1.8 and 1.12), not just 1.15.2. I have also tried opening minecraft without optifine/forge and the same problem occurs.
MC-180685
Skin has black likes - wont upload properly
Resolved
Duplicate
3
Same here i Noticed This Bugs Yesterday at 7:00 PM(GMT+7) when i was conected to Hypixel with Hyperium Client,then i go back to Optifine and same result,go to vanilla and same as all the two variant
to reproduce a bug is : 1. Upload Slim type skin on minecraft.net/On Minecraft Launcher
2.Select Slim Type Skin
3.then when join any minecaft game(Singleplayer/Multiplayer) skin apear to be steve variant or classic variant
also theres a bug that skin doesnt update immidiately after uploaded like it was before the bug apears