White sky pixels visible through custom 3D models from resource packs

When using custom 3D models created via resource packs, small white pixels appear inside the model.
These pixels seem to come from the sky, as if the skybox is rendered through the model, creating visible holes.

This issue is especially noticeable when the sky is bright or white. The model itself is not transparent and the textures are correctly configured.

Notice: These pixels appear between blocks at their edges.