Responding to this topic that we figured out the issue and a solution! Turns out WebGL wasn't enabled.
I'll be updating the game to include this fix :)
Turns out I can't include this fix with the game, as it actually breaks stuff for those that don't have the bug. If you experience missing patterns, or patterns overlaying on top of clothes incorrectly (like a big square), then you should try and turn on hardware acceleration in your browser (like Chrome). You can find instructions here: https://www.lifewire.com/hardware-acceleration-in-chrome-4125122
Restart your computer, then try and run the game again. If that still doesn't work, you can contact me for the fix, you can join the Discord here and I'll hand out further instructions.