Hello, please advise how to deal with scuffs on 12 pro silver (specifically on stainless steel) if the phone is in a case all the time. How can you get rid of streaks?

I can think of several ways but I would not do any of them because they might invalidate your warranty should you need to have Apple take a look at the device for another issue. Doing it might be considered to be unauthorized modifications.

Click on this link to take you to the page about Apple warranties, then select your device and country --> https://www.apple.com/legal/warranty/