Such things are happening quite a lot lately, but it doesn't seem to be for all players at the same time.
A few nights ago on Baltic some players reported a huge full sector darbar over A41. For most of us, there was none visible at all. Only when they moved into my sector, the darbar suddenly jumped to full red. I was playing for some time at that point.
Yesterday I was on a 23k bombing run. Suddenly a darbar popped up in my sector, but at that time the enemy con was already in visual range. We weren't close to any sector border, nor did the adjacent sectors show any prior darbar.
Had a few converstions with fellow players experiencing similar stuff.