Versions
Forge: 14.23.5.2860
OptiFine: preview_OptiFine_1.12.2_HD_U_G6_pre1
GTCEu: gregtech-1.12.2-2.3.1-beta

Texture bug appears when using Optifine with Anisotropic Filtering set to any mode, this issue is on both your version of the GregTech CEu mod and the original GregTech CE.

As you can see, when the Anisotropic filtering setting is turned off, the bug does not appear.

I apologize if my English is wrong, I'm from Ukraine))

do you have any other mods installed, (like a certan funny asm mod)

Yes, I have loliasm-5.3 (reworking of the VanillaFix mod), but if you remove this mod, nothing will change and the texture bug remains.

you have gregicality legacy and gtce installed, instead of ceu, going to close this issue

@htmlcsjs
This happens in your GregTech CEu mod, here is a test on a clean build of Minecraft in the screenshot. I just pointed out that this problem is present on both versions of the GregTech mod

can confirm, however we probably cant fix it because of its probally an incompatibility with codechickenlib and optifine.

@htmlcsjs Do you think it makes sense to write to the author of the CodeChickenLib library? Perhaps he can fix this incompatibility.

https://github.com/TheCBProject/CodeChickenLib/issues

@htmlcsjs Do you think it makes sense to write to the author of the CodeChickenLib library? Perhaps he can fix this incompatibility.

https://github.com/TheCBProject/CodeChickenLib/issues

@NorthHusky it will have no use as the 1.12 version of CCL is unsupported by the author and he will no provide no fix for this.

@Irgendwer01 Do you know how you can replace the anisotropic filtering setting so that there are no bugs on the water?
Anisotropic Filtering: 2

Anisotropic Filtering: 0

Given this is a non game breaking optifine issue, I am closing this.