Going to go ahead and add my voice into the mix as Zhexos said to make a bug report here about the audio stuttering/glitching.


Date & Time: Start of Endwalker's Launch
Frequency:
World name: Gilgamesh
Character name: Grimno
Retainer name: N/A
NPC name: N/A
Monster name: N/A
Class/Level: White Mage 90
Party or solo: Both
In-game time: Any
Area and coordinates: Anywhere. Sometimes trials, sometimes raids, sometimes FATEs, sometimes in towns. Some instances are worst then others.
Housing: Can't enter house due to server load.

Questions from Zhexos' post in the Technical Support thread:
1. What are your Character and Object Quantity current set to?
Max: Lowering it had no effect
2. What other applications do you have running in the background while playing FFXIV?
Firefox and Discord
3. Is your audio device set as the Default Device?
Yes
4. Would the issue persist when playing the game in DirectX 9?
It's not as bad, but DirectX 9 will cause the game to freeze up on loading, crash, and on some occasions not load in assets like Boss enemies.
5. If you use a gamepad, does the issue persist when you unplug the gamepad?
I don't use a gamepad.
6. Does the issue persist when you have the in-game Equalizer Mode set to Standard?
Yes
7. Does the issue persist when the Listening Position is set closer to the Character?
It does persist when set to 100, but it's not as bad at times.

Downloaded the free trial of the "Spatial Audio Pack"
Crackling Audio goes away when turned on and equalizer set to Standard
Crackling Audio returns if turned on and equalizer is set to bass/treble/voice

Sound effects, specifically combat sound effects, sound muffled and like it's underwater when the audio pack is turned on.

■ PC Specs

To obtain the system information, open the FFXIV launcher and select Config → System Information → Display.

-=-=-=-=- System Information -=-=-=-=-

SYSTEM_OS Windows 10 Home 64-bit (6.2, Build 9200) (19041.vb_release.191206-1406)
SYSTEM_CPU AMD FX(tm)-8320 Eight-Core Processor (8 CPUs), ~3.5GHz
SYSTEM_CORE_NUM SYSTEM_CORE_LOGIC 8 SYSTEM_CORE_PHYSICS 4
SYSTEM_BIOS 2201
SYSTEM_LANGUAGE English (Regional Setting: English)
SYSTEM_MEMORY 16283.504MB
SYSTEM_VIRTUAL_MEMORY 134217727.875MB
SYSTEM_PAGE_FILE 22387.609MB
SYSTEM_STORAGE C:\ SYSTEM_HARDDISK_DRIVE SYSTEM_TOTALDISC_SPACE 464.712GB SYSTEM_FREEDISC_SPACE 118.590GB
SYSTEM_DIRECTX_VERSION DirectX 12
SYSTEM_GRAPHICS AMD Radeon RX 5600 XT
SYSTEM_GRAPHICS_DEVICE \\.\DISPLAY1
SYSTEM_GRAPHICS_CHIP AMD Radeon Graphics Processor (0x731F)
SYSTEM_GRAPHICS_MAKER Advanced Micro Devices, Inc.
SYSTEM_GRAPHICS_VRAM 6107.730 MB
SYSTEM_GRAPHICS_SHARED_VRAM 8141.752 MB
SYSTEM_GRAPHICS_DAC Internal DAC(400MHz)
SYSTEM_GRAPHICS_DISPLAY_MODE 1920 x 1080 (32 bit) (60Hz)
SYSTEM_GRAPHICS_DRIVER C:\WINDOWS\System32\DriverStore\FileRepository\u0372545.inf_amd64_56d459236871c3f2\B372333\aticfx64.dll,C:\WINDOWS\System32\DriverStore\FileRepository\u0372545.inf_amd64_56d459236871c3f2\B372333\aticfx64.dll,C:\WINDOWS\System32\DriverStore\FileRepository\u0372545.inf_amd64_56d459236871c3f2\B372333\aticfx64.dll,C:\WINDOWS\System32\DriverStore\FileRepository\u0372545.inf_amd64_56d459236871c3f2\B372333\amdxc64.dll
SYSTEM_GRAPHICS_DRIVER_VERSION 30.00.13025.5005
SYSTEM_GRAPHICS_DRIVER_DATE 10/4/2021 19:00:00
SYSTEM_GRAPHICS_DRIVER_LANGUAGE English
3.0
SYSTEM_GRAPHICS_PIXEL_SHADER 3.0
SYSTEM_GRAPHICS_VERTEX_TEXTURE SYSTEM_SUPPORT
SYSTEM_GRAPHICS AMD Radeon RX 5600 XT
SYSTEM_GRAPHICS_DEVICE \\.\DISPLAY2
SYSTEM_GRAPHICS_CHIP AMD Radeon Graphics Processor (0x731F)
SYSTEM_GRAPHICS_MAKER Advanced Micro Devices, Inc.
SYSTEM_GRAPHICS_VRAM 6107.730 MB
SYSTEM_GRAPHICS_SHARED_VRAM 8141.752 MB
SYSTEM_GRAPHICS_DAC Internal DAC(400MHz)
SYSTEM_GRAPHICS_DISPLAY_MODE 1920 x 1080 (32 bit) (60Hz)
SYSTEM_GRAPHICS_DRIVER C:\WINDOWS\System32\DriverStore\FileRepository\u0372545.inf_amd64_56d459236871c3f2\B372333\aticfx64.dll,C:\WINDOWS\System32\DriverStore\FileRepository\u0372545.inf_amd64_56d459236871c3f2\B372333\aticfx64.dll,C:\WINDOWS\System32\DriverStore\FileRepository\u0372545.inf_amd64_56d459236871c3f2\B372333\aticfx64.dll,C:\WINDOWS\System32\DriverStore\FileRepository\u0372545.inf_amd64_56d459236871c3f2\B372333\amdxc64.dll
SYSTEM_GRAPHICS_DRIVER_VERSION 30.00.13025.5005
SYSTEM_GRAPHICS_DRIVER_DATE 10/4/2021 19:00:00
SYSTEM_GRAPHICS_DRIVER_LANGUAGE English
3.0
SYSTEM_GRAPHICS_PIXEL_SHADER 3.0
SYSTEM_GRAPHICS_VERTEX_TEXTURE SYSTEM_SUPPORT
SYSTEM_SOUND Headphones (ROCCAT Juke)
SYSTEM_SOUND_DEVICE_ID {AC9B477D-C794-4507-B152-8D1E78A12AFC}
SYSTEM_SOUND_DEVICE_NAME USBAUDIO.sys
SYSTEM_SOUND_DRIVER_VERSION 10.0.19041.1202
SYSTEM_SOUND_DRIVER_LANGUAGE English
SYSTEM_SOUND_DRIVER_DATE 8/25/2021 19:00:00
SYSTEM_INPUT {6F1D2B60-D5A0-11CF-BFC7444553540000}
SYSTEM_INPUT_NAME Mouse
SYSTEM_INPUT_REMARKS SYSTEM_GAMEPAD_AXIS 3 SYSTEM_GAMEPAD_BUTTON 8 SYSTEM_GAMEPAD_FOV 0
SYSTEM_INPUT {6F1D2B61-D5A0-11CF-BFC7444553540000}
SYSTEM_INPUT_NAME Keyboard
SYSTEM_INPUT_REMARKS SYSTEM_GAMEPAD_AXIS 0 SYSTEM_GAMEPAD_BUTTON 128 SYSTEM_GAMEPAD_FOV 0
SYSTEM_INPUT {00CAC310-6169-11EA-8001444553540000}
SYSTEM_INPUT_NAME ROCCAT Juke
SYSTEM_INPUT_REMARKS SYSTEM_GAMEPAD_AXIS 1 SYSTEM_GAMEPAD_BUTTON 5 SYSTEM_GAMEPAD_FOV 0
SYSTEM_INPUT {3836A2E0-6F24-11E7-8001444553540000}
SYSTEM_INPUT_NAME USB Receiver
SYSTEM_INPUT_REMARKS SYSTEM_GAMEPAD_AXIS 0 SYSTEM_GAMEPAD_BUTTON 0 SYSTEM_GAMEPAD_FOV 0
SYSTEM_INPUT {7A275AE0-F2DA-11E5-8001444553540000}
SYSTEM_INPUT_NAME C-Media USB Audio Device
SYSTEM_INPUT_REMARKS SYSTEM_GAMEPAD_AXIS 1 SYSTEM_GAMEPAD_BUTTON 5 SYSTEM_GAMEPAD_FOV 0
SYSTEM_INPUT {383877A0-6F24-11E7-8002444553540000}
SYSTEM_INPUT_NAME USB Receiver
SYSTEM_INPUT_REMARKS SYSTEM_GAMEPAD_AXIS 0 SYSTEM_GAMEPAD_BUTTON 652 SYSTEM_GAMEPAD_FOV 0
SYSTEM_INPUT {38389EB0-6F24-11E7-8003444553540000}
SYSTEM_INPUT_NAME USB Receiver
SYSTEM_INPUT_REMARKS SYSTEM_GAMEPAD_AXIS 0 SYSTEM_GAMEPAD_BUTTON 0 SYSTEM_GAMEPAD_FOV 0

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Others have spoken about the idea of possibly allowing us to swap back to 5.55 Audio System, and I'm absolutely in agreement.
Right now it just seems the "solution" is to buy better hardware, but the fact that even newer processors are having issues, not just "Older then 10 years" (mine is 9 years old. Not new, but not 10+ years) means that there's a chance that they'd still have crackling audio regardless.