When playing audio quickly, there's sometimes "spike" in volume at the start of a clip regardless of using Animator play audio or animating the source on.
Logarithmic Volume Rolloff being used seems to correlate with the issue.
Test avatar:
avtr_43d5dc71-951c-4e46-b8f1-4874ab4aee3e
Equip the rifle in the radial menu items, set fire rate to 100. Click infinite ammo. Use right hand fist gesture to fire.