https://github.com/RuffleSteels/Firorize/blob/master/src/main/resources/assets/firorize/textures/block/arrow_left.png

Textures should always be square and the size should always be a power of two, UV's can be used to pull the portion of what you need, odd sized textures end up dropping the mipmap level, in this case all the way to 0.

Texture firorize:block/arrow_left with size 12x7 limits mip level from 3 to 0

Fixed with 76b9e4b

The texture should be 16x16 since 12 isn't a power of two

yep ofc my bad

properly fixed now