We are all different and what works for one person does not necessarily work for another. I have a low BMI 18.5 and have read a lot of posts of individuals with low BMI having issues with Dexcom CGM readings. For me, line of sight is very important. I don’t even need much compression to cause a compression low, by wearing the sensor just above the belly button, all I need to do is turn onto my stomach on mattress and even with holding myself up with my arms so transmitter fully touches the mattress without compression, my BG drops about 50 points with receiver just 2 feet away on night table. If I snuggle a partner and just have transmitter touch skin of partner I get total signal loss.
There is an ongoing argument if it is a bluetooth signal issue or filament in fluid issue. In reality it is probably a combination of both depending on individual and situation and equipment. I am on Dexcom G5 and receiver. Even with Dexcom there are several variables such as if you are using a receiver or a phone, which app you are using if with a phone, which transmitter G4,G5, or G6 and if you are on blue tooth which BT version you have and which Dexcom version of software you are running. My mattress is memory foam and maybe that is even a contributor.
You are lucky that your son’s signal will go through mattress, floor, brick walls and leap tall buildings in a single bound. I am not so lucky so obviously what works or does not work for me does not affect your situation. You claim your son still gets compression lows from time to time. I keep line of sight for past 8 months and have not had 1 compression low.
Belly is best position for me and by using opsite, have never had a sensor pull out due to folding skin, sports, furniture, seat belts etc. and by keeping line of sight between transmitter and receiver never lose or distort signal when within 20 unobstructed feet between transmitter and receiver.