If you need a workaround for this for the time being, delete the __Scale value Instances out from under the scaled character’s Humanoid (the OriginalSize values can be left alone). This will work as long as you don’t need to dynamically adjust the BodyHeightScale etc, you’ll still be able to use ScaleTo dynamically even without the __Scale values being there.
It’s some kind of very rare edge case with the order / way the __Scale values arrive on the client. We’ll need to do more debugging to work out the root cause.