Hello, the reason the image shrinks is that you are tweening the deformation of the vertices of the mesh. Please delete the deformation keyframes and instead parent the mesh to a bone, and rotate the bone to get the correct result.
您好，图像缩小的原因是您正在补间网格顶点的变形。 请删除变形关键帧，然后将网格作为骨骼的父对象，然后旋转骨骼以获得正确的结果。

It is as Erika said. While you can rotate mesh vertices, it is really just changing their position. When interpolating between deform keys, the vertices always move in a straight line.
就像Erika说的那样。虽然你可以旋转网格顶点，但其实只是改变它们的位置。当在变形键之间进行插值时，顶点总是在一条直线上移动。