In single player, multiplayer, and realms I cannot see skins or player heads, they are all default Steve's and Alex's. I've confirmed this in 1.8 - 1.16.2 I've seen this bug happen a few times online but nobody seems to have found a way to fix it. I've checked everything including seeing if my antivirus was blocking files, or seeing if my java was updated. Please respond I've had this problem for almost a month now.  If it helps at all, I have another Minecraft bug where it opens the launcher twice so I have to remove one with task manager before the game will launch. I've sent screenshots attached with all the info I've stated.