Your device specification is wrong, at least your CPU.
Core i5-5300U or i5-4300U?
Check this out. Similar form factor. Compare your hardware before you start, but seem to be good.
1040 G2 vs. 840 G2
The fan speed is running constantly or changing the rpm?
Run anything in the background?
Getting warm/heat the cpu by some activity or it is not related with the high fan speed?
The Opencore is load the original Bios/ACPI table, so in theory the same like on Windows. - So the fan speed.
Separate the two image display problems.
1. when the colors are correct but occasionally flashes and inverts the image.
2. when the colors are distorted but not flashing. (First picture with the Hackintool System tab)
Which on is common?
0.74 Bios is the latest and not related. Our devices are...
#109 - You had a graphic acceleration in that picture. Which version of Big Sur was it? What did you do differently that you don't have now?
Have you installed the Legacy Patcher? - Screenshot 2 showing “no kext loaded”.
Please do not use the VGA port until you get everything on the main...
I assume it's correct.
Maybe, you don't need to use: @0,display-link-component-bits and @0,display-pixel-component-bits. Change the value or comment out.
Search Mobile GPU and look at this.
But first, take a shot with 11.2.3.
I would say it is not supported by the Legacy Patcher yet.
My thought is you should try 11.2.3, since almost everything works only this one doesn't.
If not, we will look deeper.
Edit: Your EDID is different, you have a Full HD screen if i'm right. You can try this.