OK, sanity check time please...............

Goggles v2, DJI Air Unit. DJI, not WTFOS.

Sudden change in flight that while still shows full set of signal bars, and chosen channel bottom left, its shifted to RED and stayed red still showing full bars. This indicates what?

All I can find is ONE instance of:-


440
00:01:06,450 --> 00:01:06,633
signal:4 ch:3 flightTime:67 uavBat:23.5V glsBat:47% uavBatCells:6 glsBatCells:0 delay:27ms bitrate:25.2Mbps rcSignal:0

441
00:01:06,633 --> 00:01:06,783
signal:4 ch:65535 flightTime:67 uavBat:23.5V glsBat:47% uavBatCells:6 glsBatCells:0 delay:29ms bitrate:25.1Mbps rcSignal:0

442
00:01:06,783 --> 00:01:06,900
signal:4 ch:3 flightTime:67 uavBat:23.5V glsBat:47% uavBatCells:6 glsBatCells:0 delay:23ms bitrate:25.1Mbps rcSignal:0

Try to ignore that channel strength indicator in the bottom left and just use the "Mbps" and latency "ms" values on the bottom right to determine signal strength / quality.

DJI borked that channel signal strength indicator a number of firmware revisions ago and never bothered to fix it, so it's been left unreliable and buggy on the latest V01.00.xx.xx firmware versions. I wish you could just switch that signal indicator off with an option in the goggles menu, but unfortunately you can't and the fact that it turns red when the signal strength and quality is still perfectly fine is even more annoying because when that happens it automatically draws your eyes to the bottom left corner of the screen.

EDIT: If you're feeling brave you can move / remove the DJI HUD elements by editing an XML file on the goggles, but it's not a procedure for the faint-hearted and your goggles do need to be rooted to enable you to do that. You can find detailed instructions HERE.