It seemed something similar happened some years ago.
https://bugs.mojang.com/browse/WEB-1061
There are thousands of skin files not working right now.
Here some examples:
https://textures.minecraft.net/texture/9636dee806ba47a2c40e95b57a12f37de6c2e677f2160132a07e24eeffa6
https://textures.minecraft.net/texture/cbc826aaafb8dbf67881e68944414f13985064a3f8f044d8edfb4443e76ba
https://textures.minecraft.net/texture/5a5153479d9f146a5ee3c9e218f5e7e84c4fa375e4f86d31772ba71f6468
https://textures.minecraft.net/texture/904f1a55943c594e7119e884c5da2a2bca8e7e6516a0649aa7e55658e0e9
Here one that's still working:
https://textures.minecraft.net/texture/58bad2c2d483741ae0a7b4a4bf43421270b0e5deb464d4f85fd7688b1a60b4e9
@@unknown Hello Le3awe, i think my report is not resolved in anyway.
The marked Duplicate MC-132351 is a wrong report because Plants also dont grow under soild Blocks in older Versions for a long long time( You can see it on one of my Screenshoots is from 1.12.2 and not growing under Sandstone like it allways was).
This report is about the changes to the Opacity of Farmland,
The Post from Shaijana is another bug where yesterday 18000 heads got removed but it seems to have been reverted for now. Im not gone post the bug report because they seem to be not related.
At the moment we are back to the old problem: around ~50 heads are working.
Here 5 example of missing heads:
https://textures.minecraft.net/texture/caf039bec1fc1fb75196092b26e631f37a87dff143fc18297798d47c5eaaf
https://textures.minecraft.net/texture/21ea825150b06e65e2ceb593afe342dca56dda12bf6c9696fb82f90dcd423ab
https://textures.minecraft.net/texture/994a7dfbad60295192b9fbbccc013dcd5c7f738501b0a029896ccd141e16954b
https://textures.minecraft.net/texture/22d023d1c3fca0a0d64695e70b112cfa580072bbec072aaca0bcee5d131b70e3
https://textures.minecraft.net/texture/9e28a0064a04ccfb4306ac44e594d14495877f20e86346ec6d51cb78cc6ece2c