Custom blocks using the blend or blend_to_opaque render methods flicker when moved by a piston. In particular, it appears that the opacity of the texture changes. This issue was not observed with other render methods.

Demonstration

The attached video demonstrates this issue. Notice the flicker mid-move.

Reproduction

This example is taken from the packs in the attached world for convenience. This world can be opened (in Minecraft Preview) for inspection or unzipped to access the code associated with such.