The top texture of the flags has obvious z-fighting.

Mod list:
configured-1.5.1-1.18.1.jar
MouseTweaks-forge-mc1.18-2.18.jar
ferritecore-4.0.0-forge.jar
AI-Improvements-1.18-0.4.0.jar
ToastControl-1.18.1-6.0.0.jar
jei-1.18.1-9.1.0.46.jar
TesseractAPI-1.18.1-0.1.jar
forge-1.18.1-39.0.5-universal.jar
appleskin-forge-mc1.18-2.2.0.jar
flywheel-forge-1.18-0.4.2-rc.jar
supplementaries-1.18-1.0.7.jar
GameMenuModOption-1.18-Forge-1.13.jar
create-mc1.18.1_v0.4a.jar
Clumps-forge-1.18.1-8.0.2.jar
selene-1.18-1.11.jar
Controlling-forge-1.18-9.0.4.jar
Placebo-1.18.1-6.0.1.jar
citadel-1.10.3-1.18.jar
alexsmobs-1.14.3.jar

hmm I can't replicate. Must be a conflict with one of those mods. does it happen on only 1 orientation?

It happens in all orientations.

The culprit seems to be create/flywheel, since it only happens with those installed.

Nevermind, it seems to happen even with just supplementaries and selenelib, no other mods installed.

yeah also cause I usually have flywheel installed. I'm not sure what's going on here since it doesn't happen with I boot up with it with the mod alone. Weird thing is that item seems to work fine despite it using the exact same renderer as the block

If its any help, here is a debug crash log:
crash-2021-12-20_22.39.09-client.txt

It seems to be fixed in the newest version. Thanks!