Same symptoms seen here, after 1.5.80 RC firmware I am getting weak signal much much sooner, even at 150m with line of sight and channels clear of interference. (auto)
The behaviour looks like the RC broadcast DB strength has been reduced by 10-20%
There is a good likelihood that a reduction in transmitting power could have been introduced In the basic controller hardware, or by way of firmware updating, would be my guess.
Signal strength had been taken for granted as newer models were developed and introduced, however this aspect of a quadcopters capabilities could be reduced at any time, or offered to individuals, or groups via special permitting request, similar to that of the 333 exemption, and to those who accept responsibility by providing credit card information as an alternative.
Many have sought to increase the models standard battery power supply, adapting additional power packs and altering the main battery.
Frankly, I wouldn't be surprised to see additional tradeoffs within such upcoming firmware updates, as such updates may not necessarily be in the best interest of the user, but be more geared to liability concerns of the manufacturer.
While adding an additional source of power supply may provide greater reliability, and quell concerns that the model may fall from the sky as result of recently introduced f/w updates, such additional power may serve to encourage some to then use this power to go where no man has gone before, so to speak, further compromising the LOS mandate requested by the FAA.
I'm of the opinion that signal strength had been maximized of recent to hopefully improve control over the model, particularly under adverse conditions, and not necessarily to push the limits of its flight path.
Again, while all this may or may not be a factor the manufacturer would consider should they decide to diminish the signal strength of the model, and nothing conclusive, it is food for thought. : )