@dyiing I got hurt when I was attacking a creeper in a cave and I was wearing iron armor no enchants. Its a low chance though. The creeper attacked me from a distance like it hit me instead of exploding. I can try and get a clip.
@prominecraft There might be 2 reasons why you can't download Optifine.
Uninstall Phosphor, Sodium, Lithium as it will affect or doesn't allow you to download Otifine.
Sometimes it doesn't install Optifine completely so you will have to exit out of the client and reopen it through the minecraft launcher and reinstall it through the addon market. If this continues just repeat it.
@dyiing it's taxing to fly 28k blocks to check, but I never saw any evidence that the effect loops. It might loop past the worldborder, but that's even harder to check.
"Opacity" as displayed in my attached screenshots may have something to do with the lighting model. Like, if they glow red because they have bright ambient lighting and nothing else, that ambient value might be somehow affected by the camera coordinate.
Oh, if it wasn't clear in my original post, this is dependent on the CAMERA coordinate, not the block or player coordinate.
@dyiing I think it happens to me when I use forge with optifine in 1.16.5, entities, water textures, or particles do not load me. removing the optifine solves it but it is quite an important mod for some and I think they should fix it.