Just to keep the facts clear, NOT unique to both pro models. There was a totally separate software issue relating to focus, which was fixed in ios 14.2
The iPhone 12 , 12 mini, and 12 Pro can all take macro photos at the usual ~3 inch range. If you buy any of those models and you are on 14.2 or higher, you have no issue and should stop reading this thread!
The Pro Max and ONLY the Pro Max has a hardware limitation that increases min focus distance to around 5”, thus it is very significantly less capable at macro photography. this is a design compromise Apple made when introducing the larger sensor, and sensorshift stabilization, found in the pro max.
While many of us feel that Apple made a huge mistake here, it is a design choice they made and so from their perspective, there is nothing to fix. so there will be no update/fix!! if you can’t live with it ,return it. A lot of people are doing so, myself included.