The textures for the interior of the regular formwork block's top (or interior) is broken, but the texture for the rebar formwork block works fine:

Running on:
MultiMC 5
Eclipse Temurin jdk-17.0.9.9-hotspot
Minecraft 1.20.1
Forge 47.3.0 (Also tested 47.3.11)
Create 0.5.1.i
Create: The Factory Must Grow 0.9.3 (Also tested 0.9.2)
(Tested with no other mods)

Just tested, version 0.8.0b of Create: The Factory Must Grow (chosen by criterium of most downloaded version) doesn't have this issue