Screen flickering but at 30 degree and less than that it works fine

A flickering screen based on angle is likely a backlight cable issue from the T-CON board to the display assembly. A different cable brings the power to the T-CON board.

As you can see the four cables between the T-CON and the display assembly these cables flex as you open and close the lid so it's possible the cable has fatigued or the chin plate under the LCD panel has been damaged so the cable passing behind was damaged.

Is the Chin plate visibly damaged? The space between the uppercase and lid is very tight so anything resting near the hinges can damage it.

You could carefully unplug the backlight cable see if reseating it clears the problem if the chin plate is not damaged. If that fails replacing or repairing the cable is a bit of Brain Surgery! There are people with the tools and skills to do it but in the process there might be some physical damage to the lid trying to open it.

I would recommend hunting down a dead system to transplant the display. Here's the guide MacBook Air 13" Late 2020 Screen Replacement or just get the new display assembly as in the end the availability of even a used display is hard!