Minecraft 1.12.2 Forge Final
supermartijn642corelib-1.0.7-mc1.12.jar
tesseract-1.0.21-mc1.12.jar

My head hurts but I care deeply about your project so here some screenshots for sure affects Pixelmon not sure if other mods are affected.

My modpack version

https://www.curseforge.com/minecraft/modpacks/fiction-friction/files/3351206

Are you mutating graphics verts or lighting? I am really confused how your mod affects block models in any capacity.

Tesseract uses the same code as the end portal.

I am unable to replicate this, are you sure it is caused by Tesseract?
Are there any steps I should take for it to happen?

Only certain angles

No its very hit and miss

If you ever wanted to jump on my server I can op you for testing purposes.

It does not happen unless you are on a dedicated server - forgot to mention.

I am getting ready for bed though ... so it may be later if you wanted to tell me your ingame name I can op you before I sleep.

https://youtu.be/f_qfEMK8w80

Edit what I mean't to say was "Removing phosphor has no affect." also I hate outros XD

It should be fixed now in version 1.0.22.

Thank you testing now.

It is fixed.

Great, thank you for reporting the issue and helping me out!

Anytime.