[Bug] Block Border Incorrect Rendering

[ThisIsMystic]

Description of Issue

When looking at blocks using Fabulous graphics, in OptiFine 1.16.1_HD_U_G2, sometimes the block outline border can randomly glitch out and pixelate into orange/blue squares.

Steps to Reproduce

1. Turn on Fabulous graphics
2. Turn on Fast Render
3. Look at blocks. This 3rd step is extremely vague because it's impossible to know when it may happen, it just happens at random. There is no set way of triggering it on purpose, it just has to happen naturally. If it does happen, it happens for an extremely short burst of time. (It took me 13 different tries just to get one frame of the issue captured.)

OptiFine Version

OptiFine 1.16.1_HD_U_G2

Installation Method

Optifine Installer

Prior Testing

Does not happen in vanilla. Only when using Optifine. I started using Fabulous graphics more in pre11, and I did notice this issue back then as well.

Additional Information

I apologize for a rather vague guide on reproducing this, but there is no way to trigger this on purpose. You just have to be lucky enough to spot it. If it may have something to do with my system specs, here are my system specs:
i7-8550U @ 1.80ghz
8gb of ram (single stick), 3gb dedicated to Minecraft
Intel UHD 620 (integrated graphics)

[UDPSendToFailed]

I get the same issue with UHD 620 on i7 10510U, I can mostly reproduce it when I'm near lots of item frames and chests. Also when this happens, sometimes my game just freezes but keeps running, so the graphical part stops, but I'm still able to chat with the T key although I can't see anything of it, but it gets sent and the log continues.