Just got the answer. They made the buttons flat, so that no lining is needed. They don‘t think it will cause scratches.
Here is the reply I got from Pitaka about no soft padding on the back of the metal buttons of the MagEz Pro 4 case.
Keep in mind that the finish is the exact same on the outside of the buttons as the inside, there is difference.
Reply from Patika:
Thanks for your email, this is Iris from PITAKA team and I am glad to help here. •ᴗ•
I receive your message and understand your worries. Please note the volume button inside is made of PTU material and the outside is made of metal. The metal part will not attach your phone directly and will not do damage to your phone. Please do not worry.
If you have any issues or worries, please feel free to let me know and I am always here to help.
For further questions, please feel free to contact us at any time.
Thanks~