Bug Timeline playback bug - character jittering

Please see this video for details.

First 7 seconds : timeline mouse drag : hard jittering.
As if the frame rendered like this : timeline animation - animator's animation, then again jump back and forth.

The rest : timeline playing : small jittering, can be noticed with camera shake and character's hair dynamic.

Camera shake is not intended, it is by-product of this bug. Because the character is jittering from the bug, the cinemachine which aims at character head will shiver along as result.

Why is this happening ? If the timeline playback can ignore the character's own Animator's animation and override it completely, it will not be like this. So I suggest this is a bug. Should I fire a bug report ?

Thankyou in advance for looking into this issue !