I just updated both of my ADC-V721 cameras and notes a significant loss in wireless signal strength on both devices. On the old firmware 0100d6 the signal was 99%, after the update to firmware 0100f4 the signal fell to 85%. See before and after pictures…
Keep in mind when applying new firmware this would cause a full reboot of the cameras and they would reconnect to wifi, possibly resulting in a different reported strength. However in this case, the new firmware for that camera model improves its Wifi signal reporting and allows more acute measurements. You will probably notice some differences from before on the reported level.
Signal naturally fluctuates, and the camera can report fluctuations a little better it seems. It looks like they are averaging about 90% currently. It should have no functional impact as the wireless link quality reported still shows near or at 100%.