Prefix disappeared in animationclip and may cause some problem

Here I have got some character model with blendshapes on my project, it run correctly on Unity 2019. But after my project was upgraded to fit Unity 2020, some error caused when the game was running some timeline on the local server for testing:

After muting track by track, I found that some animation may cause this error. And these animations have something wrong with their blendshapes. In fact some part of their blendshapes named with "m_" prefix.
These prefix shows correctly on MeshRenderer but missing on Animation view.


At first I was thinking about if it is only happened on Unity 2020, but found the same display on Unity 2019. However there is nothing wrong when playing in Unity 2019. So which wrong causes this error in deed?