This happens even in previous versions of Minecraft

When I log on any server, on a version previous to 1.13, skins don't show up, but they used to do. This is not a problem with the server being in "offline mode" because it happens even on Hypixel, when normally skins DO show up. I reinstalled every bit that's related to Minecraft, even went on my alt, to check if it still happens, and it does. It's not the fault of my Wi-Fi, because I switched to the WiFI i host on my phone. I checked on a VM to see if it happens, and it works perfectly fine. I found a "fix" to delete the skins folder from the assets folder in .minecraft, and it worked for a while, but it doesn't work anymore.