I had the same issue. Exchanged the phones for more than 3 times in the Apple store, but all the new ones I received had the same issue.
Finally returned the phone and received full refund.
Found a small mobile store in my neighborhood and requested him to find a iPhone 12 Pro Max with a production date of November 2020 or earlier.
He made many calls to his suppliers from various part of the country and found a phone which was assembled in November 2020.
Now the phone I bought doesn’t have the issue.
Peace of mind at last.
Thanks to the small mobile shop friend.
All started in October 2020 (with extended return date due to year end festival offer) and ended well in February 2021. But lost lot of branded screen protectors and petrol for the trips.