After we upgraded our program to ArcGIS Pro 3.4, many things went wrong. Many buttons with size "middle" will only show icons without texts. DockPanes hosting a winform using WindowsFormsHost will totally mess up the display. They were working fine before version 3.4. Hope ESRI can fix these issues soon.
Here are a screen shot of Pro 3.4 and one before Pro 3.4:

