I also have the exact same problem. Here is an example of what the crackling sound looks like.
https://youtu.be/ibbQgmdClFU?t=1650
Action
Action Version: 4.27.1
Recording Resolution: Original (2160p)
Recording Mode: Live Streaming - Game & Applications
Windows and Hardware
OS: Windows 11
Video Card: Nvidia GeForce RTX 2080 Ti
Video Driver Version: 496.76
CPU brand and model: Intel Core i9 9900K
Motherboard brand and model: MSI MPG Z390I GAMING EDGE AC
Memory: 32 GB
Monitor Resolution: 3840x2160
Problem Description
Game/App Problem: Microsoft Flight Simulator (2020)
Error Type: Crackling noise
Video Editor: N/A
Description: During live broadcast and recording, Action! seems to make crackling noises in the result. It seems that it's occuring when it's trying to stream and record low-frequency sounds of jet engine spool. It reminds me of a phenomenon if you have a cheap subwoofer, and trying to play heavy bass music, and the subwoofer just couldn't make the sound so it crackles on sounds below a certain frequency.