Weird green flickering on rendered video in After Effects and all my renders have these random green frames that are not present in the timelines. I had the same problem, the reason behind those glitches is the codec of file (h264, mov, etc).

Step 01

• Open media encoder, and to import your source files or the Composition to render.
• Choose a lossless codec as ProRes 444 or, under quicktime, DNxHR 444 10 bit. You may need to download the DNxHR codec.
• Render your files with media encoder
• In after effects, in your hierarchy, where imported files are listed, right click on your old footage.
• Choose "Replace footage" and then click on "files"
• Select your newly rendered footage and click ok

If not solved, try these steps below.

Step 02

• Go to Preferences > Import. Then Deselect "Enable hardware accelerated decoding" under Video Footage.
• Then go to Preferences > Media & Disk Cache. Then Click "Empty Disk Cache" and "Clean Database & Cache"
• Relaunch After Effects and import the files again.

Step 03

You must do these steps mentioned below in this exact order.

• Edit -> Purge -> All memory & Disk Cache
• Disable hardware acceleration in Preferences/Import
• Clear BOTH disk caches in this order Preferences/Media Cache, and then Preferences/ Disk Cache
• Close After Effects and Reboot Your PC

Doing the sequence had fixed the issue for me.

Previously taken steps

01: NVIDIA CONTROL PANEL
I tried rolling back my Nvidia display driver to an earlier version, and that also made no difference. I then updated back to the latest Nvidia driver and now the mp4 files playback and show every other frame as solid green.

02 : AFTER EFFECTS File -> Project Settings
No matter if CUDA (my system its Mercury GPU Acceleration (CUDA)) or Software (Mercury Software only) is selected - this happens.