The pack.png for the default resource pack uses an outdated grass block texture from before the Texture Update.
Images:
Default Resource Pack icon with old grass texture
Grass block after the Texture Update (sides look slightly different)
MC-178216
Default resource pack icon uses old grass block texture
Open
48
(Unassigned)
Confirmed
Gameplay
Low
Textures and models
outdated-textures, resource-pack, texture
1.15.2, 20w15a, 20w16a, 20w17a, 20w18a, ..., 25w32a, 25w33a, 25w34b, 25w35a, 25w36a
Retrieved
Why this issue is again here? It's fixed x)