Im not sure if this is a glitch, because I don't know if it's intended behavior or not: https://youtu.be/MUCwqNZIlP0 I dont know how to explain it, but here's a quick video of what it looks like (with the random tick speed turned up to 3000)

Here's the mod list I'm using:
[✔️] abnormals_core-1.16.5-3.3.0
[✔️] AI-Improvements-1.16.2-0.3.0
[✔️] alexsmobs-1.12.1
[✔️] AmbientSounds_v3.1.9_mc1.16.5
[✔️] appleskin-forge-mc1.16.x-2.1.0
[✔️] AutoRegLib-1.6-49 (1)
[✔️] BetterDungeons-1.16.4-1.2.1
[✔️] betterendforge-1.16.5-1.6.3
[✔️] BetterStrongholds-1.16.4-1.2.1
[✔️] BiomesOPlenty-1.16.5-13.1.0.482-universal
[✔️] catalogue-1.3.0-1.16.5
[✔️] citadel-1.8.1-1.16.5 (1)
[✔️] Clumps-6.0.0.27
[✔️] configured-1.2.0-1.16.3
[✔️] create-mc1.16.5_v0.3.2f
[✔️] CreativeCore_v2.2.1_mc1.16.5
[✔️] DynamicTrees-1.16.5-0.10.0-Beta25
[✔️] DynamicTreesBOP-1.16.5-2.0.6
[✔️] DynamicTreesPlus-1.16.5-0.1.0-Beta10
[✔️] DynamicTreesQuark-1.16.5-2.1.0
[✔️] DynamicTreesTerraForged-1.16.5-1.0.0
[✔️] endergetic-1.16.4-3.0.0 (1)
[✔️] entityculling-1.3.0
[✔️] extcaves-2.4
[✔️] FarmersDelight-1.16.5-0.5.0
[✔️] FastSuite-1.16.4-1.1.1
[✔️] ferritecore-2.1.0-forge
[✔️] flywheel-1.16-0.2.4
[✔️] Hwyla-forge-1.10.11-B78_1.16.2
[✔️] infernal-expansion-2.3.2
[✔️] jei-1.16.5-7.7.1.126
[✔️] lazydfu-0.1.3
[✔️] nethers_delight-2.1
[✔️] OptiFine_1.16.5_HD_U_G8
[✔️] Patchouli-1.16.4-53.2 (1)
[✔️] Placebo-1.16.5-4.6.0
[✔️] Quark-r2.4-319
[✔️] RawOre
[✔️] shutupexperimentalsettings-1.0.3
[✔️] steampowered-1.16.5-1.1.7b
[✔️] TerraForged-1.16.5-0.2.13
[✔️] unnamedanimalmod-1.0.2
[✔️] untamedwilds-1.16.5-1.4.1
[✔️] YungsApi-1.16.4-Forge-13

This is not a glitch it's just a consequence of how the cellular automata stuff works. The decaying/reappearing isn't harmful or noticeable under normal circumstances.

Thank you for the reply, like I said I didn't know if this was intentional. It is, however, very noticeable under "normal circumstances (RTS=3)", thats why I opened this thread. I noticed it and to demonstrate it for the video I turned up the RTS.

This is not a glitch it's just a consequence of how the cellular automata stuff works. The decaying/reappearing isn't harmful or noticeable under normal circumstances.