Shadow problem after changing from gamma to linear.

After distributing on the iPad, the shadow becomes strange. but, it looks good on the development PC Mac. (unity editor game view)

Here are some information to get advice on where to look.

1. This model has only material. There is no texture.

2. linear setting

3. directional light (shadow type : hard shadows)

4. my quality setting is here

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I would be grateful if someone could give me advice.

and I will provide it if you need additional information.