Both of these characters are scaled to the same number every Heartbeat. After 2 seconds the right-hand rig has a new humanoid description applied. This causes the Scale to glitch and no longer scale correctly.
Repro (script in Workspace)
Repro.rbxl (64.1 KB)
unfortunately HumanoidDescription scaling, and the scaleTo() function are not compatible with each other. At this time, if you want to scale the character with HumanoidDescription, you should only use HumanoidDescription scaling
Thank you for the response!
Are there any plans to fix this? Having to update humanoid descriptions and manually multiply height, width, and depth scaling times the actual humanoid amount is a major PITA.
It would almost be easier to just make my own scaling function, which I think defeats the purpose of ScaleTo in my use case 
can you exclusively use HumanoidDescription for scaling?
Unfortunately no, as I need to constantly rescale the avatar for my use-scale, and re-calling Humanoid:ApplyDescription is not instant.
For my use case users create TikTok-like clips and can animate the Scale of any model, including Character rigs. ApplyDescription is very slow to update, so I’ve had to resort to ScaleTo as it works mostly (Layered Clothing has delayed updates when using ScaleTo) well for my use case.
