@Khel72,
First thing, forget what I said about the flights on July 19. Nothing changed then.
I think someone more experienced is going to have to step in on a couple anomalies, but there is a recognizable pattern.
The overall signal strength has not changed much from the first recorded flights.
What is very apparent is the difference in recorded signal strength related to the location of the flights.
All of the flights I looked at were at one of four locations.
1. South, at the end of S. El Capitan at what looks like a school, out over barren, open ground. This area consistently shows the strongest signal strength for flight duration. You went out over 1200ft on one flight, and still had signal.
2. West, at the end of Natures Glenn Ave. Also flying out over open ground. This area also shows good signal strength, just not quite as good as the first one. I think the max I saw here was about 900ft.
3. A couple miles north, near what looks like a large drainage culvert. Signal strength recorded here is mediocre, but not all that bad. There were a couple anomalies here, in that you had very weak signal when only a couple hundred feet out. Mostly you didn't go much over 400ft, and still had some signal.
4. Your house. Surrounded by LOTS of other houses. The recorded signal strength here is by far the weakest. It's not all that bad actually (better than around my area), but it is noticeably less than any of the open areas. And on flight 121/122, you showed a relatively steady decline until you lost signal completely at about 800 ft.
There is also a noticeable decline in recorded signal strength as you increase altitude. Drops with distance, of course, but eyeball evaluation makes me think the rate of decline is very high when you reach (typically) about the 60 ft. range. I don't have much to speculate on that one, unless you are not keeping the flat part of the controller aimed at the drone. Signal seems to level back towards normal as you move further away. This implies (certainly does not prove) you could benefit a little by keeping the controller aimed at the drone.
Bottom line from what I can see, you don't really have an equipment problem. At least not a new one. You have better signal than I do at those ranges, but I have no way to tell what is "normal" for your flying environment. It appears that on flight 121/122 (same actual flight), you just outflew the radio range available at that location. The signal cuts completely out at the end of what is recorded as flight 121. ~30 or 40 seconds later, it struggles back in as flight 122, with the drone pretty near the same position. I have no way to know how much further (if any) it went /returned during the missing time period. I don't know if RTH brought it back, or if it was the normal programmed response of the Q500 to return to launch site if it sees a sustained loss of signal.
The flight log does not have data for the camera signal, so I can't speculate much on that until we talk more about the current level of video loss, any areas where it is better than others, the history of how it has changed, and the typical distances where you loose it.
I hope someone else can provide better info. Reading this stuff is not a strong point for me.