Minecraft 1.21.1
NeoForge
Chalk 1.6.7

Appears to cause some major log spam
latest.log

Just tested with Embeddium, then with ModernFix + Ferrite core on top (mods that can potentially cause the issue with models).
Nothing is printed in the log.

I could just remove the log messages, but it would be good to know what exactly causes the issue.
You can try testing with only Chalk and then adding mods back in in parts, to help isolate the conflict.

Also, do the chalk marks look ok in game?

Yeah they seem to look normal.

The pack I publish is called "Friends United 2.1" I believe the log spam happens in the latest version.

Can confirm the same issue in the set of mods I have but haven't figured out what exact mod is causing the issue. I've tried running with just Chalk, Embeddium, Embeddium/Rubiddium Extras, FerriteCore, and ModernFix and can't get the spam but in my large mod list (listed in the logs), I can reproduce the spam. Will update this comment once I can figure out which mods are causing the spam.
My instance is using NeoForge v21.1.21 on MC 1.21.1
Logs: https://mclo.gs/LnirNYw

AH I found the culprit; it's JourneyMap! If I run Journeymap with Chalk at all it causes the spam even during startup! And with every other mod except for JourneyMap, the spam goes away; but as soon as I install JourneyMap the spam comes back.

The version of JourneyMap I have is v1.21-6.0.0-beta.20

I'm seeing the '[Render thread/ERROR] [io.gi.mo.ch.Chalk/]: IModelData did not have expected property: FACING' spam with embeddium but not with modernfix or ferrite installed

Confirmed here, small QoL modpack with chalk and Journeymap installed, getting spam