Reproduction steps:
1. Open the attached project "ReproProj"
2. Open the “/Assets/Scenes/SampleScene.unity” Scene
3. Enter the Play Mode
4. Open Profiler (Window > Analysis > Profiler)
5. In Profiler search for “CinemachineInputAxisController“

Expected result: GC Alloc of CinemachineInputAxisController is 0 B
Actual result: CinemachineInputAxisController has GC Alloc of 384 B

Reproducible with: 3.1.1 (6000.4.0b7), 3.1.5 (6000.0.67f1, 6000.3.7f1, 6000.4.0b7, 6000.5.0a4)

Reproducible on:
Play Mode
Windows Standalone Player

Testing environment: Windows 10 Enterprise 21H2
Not reproducible on: No other environment tested

Note:
- Not reproducible after deleting the "Demo Control Value Reader" Script Component attached to "VIRTUAL CAMERA"