Thanks! I wish I had more time this week to spend on it, came in just under the wire with what I had.
The rendering hiccups are annoying, it seems to only be present in the godot web build, and happens whenever a new material is first rendered, as far as I can tell. I'll have to do some digging and see if I can pre-load them for performance.
Viewing post in Cat Tower Climb - Quest for the Sunbeam jam comments
I have spent a long time pondering this problem that was presented here, and I think I have finally gotten an understanding of it.
https://travismaynard.com/writing/caching-particle-materials-in-godot
And in the case of the web version, it's using a compatibility renderer instead of the intended renderer (Forward+), which means that it's subject to the problems occurring in this article.
Credit to the guy who found this article, (Discord Name: Vase)