I am still having issues with the RC locking in CE mode at certain places but when I move few miles from point A to point B I start to have the RC locked into FCC transmission mode and I was able to fly 800 meters without any issues. If I go back to point A the RC goes back to CE mode

The next question is why the RC is behaving this way, it is not supposed to lock in CE in the first place since I am in the US. It looks like a GPS algorithm issue but why it affects only few users? Maybe because specific users have a RC with parts / board from a specific manufacturer batch? Since DJI outsource they production to different vendors in China this issue could be affecting only a specific vendor's batch which explains why the problem is not widespreeded. This is all about DJI collecting the production data from users hardware experiencing this range issue and isolate it to the specific vendor, except if they find problematic hardware from more than one parts manufacturer.

Id say your on the edge of a no fly zone and it was starting to kick in by lowering power.
You have the air base and strip not far from you to your NW.
Check the no fly zones to see.

Thank you for your comments about the geographic location. I am aware of the no fly zone about 7 miles NW but I am testing SW all times to make sure I isolate the issue, the opposite way as far the aircraft goes but at fixed point as far the RC home point is, still far away from the no fly zone  perimeters.

Now thinking hypothetically about the no fly zone area, what do you think is the relation with the RC not operating on FCC mode but CE.
Do you mean that in CE mode the aircraft is allowed to fly a “no fly zone” from a signal range prospect?

The big question is why spot A defaults to CE and spot B defaults to FCC when they are 4 miles away from each other. Spot B is 5 miles from Santa Ana Airport.
Another point is that when I flown at spot B, I was in the LAANC warning zone, I had requested and received authorization to fly and the signal was locked in FCC automatically as soon I turned the devices on before requesting authorization.

My thoughts where that it knows you are close to these zones, and might be limiting you power/range by going into CE mode to do that, to make sure you cant reach the no fly zones.
Without knowing how the're limiting ability works for no-fly zones , this might be a explination possibly.
Hopefully some of the moderators see this and can make a comment on this for you.