GDI is the likely answer.
Gerd: I believe that the GDI differential has been tweaked or re worked slightly, I had a similar problem recently where trying to hit a bot slightly over half my NW, and having to drop several hundred k to get the hit off.
I never paid attention to the rounding of the last digit, but it was still 50.00% last week and it was still 50.00% last set. So until I experience the same thing, and check and recheck it, I will assume you did your math wrong, and theres nothing strange with that. I do my math wrong sometimes as well. The important thing is to be humble enough to go back and realize it was user error instead of assuming there is an error in the game.
Just looking up the history via earthgraphs:
this is my target, at the time of my hit, and then, just after.
2020-05-06 00:45 263 Simon De Belleville Darkblood (#255) 7,686 2,807,502 DG Alive N L
2020-05-05 23:05 257 Simon De Belleville Darkblood (#255) 7,933 2,880,499 DG Alive N
This is my country, just before my hits. I had to drop further NW to make my hits.
2020-05-06 00:40 127 SrsDrunkenPooG (#451) [Paradigm] 15,892 5,501,404 D Alive N
This is after my hits:
020-05-06 00:45 124 SrsDrunkenPooG (#451) [Paradigm] 16,334 5,665,377 D Alive N L
2.88 2is 5.76 million by my maths. 5.76 million is more than 5.5 million, yes?
(PS. I don't really care about giving away my country number in this case.)
I just tested this on 3 countries, I have marked the ones I could hit with a 'Y', all were in GDI.
Relative NW, [Target NW/My NW]
190.0% = Y
198.3% = Y
50.1% = Y
EEstats and Earthgraphs takes time to update, the nw at the time of the hit is what you have to record and the earthgraphs record says nothing about that, could be that the bot was hit just before and the real NW is lower, or that you took turns/bought something since the update. An ingame search always gives the exact NW of your target at that instant, and the NW you see on your advisor, main menu and on the right of your status bar is the exact NW of your country. The number you see in the scores list often is different from that, and its because its up to 5 minutes old, just ike earthgraphs and eestats.
Either way as far as my testing goes GDI is unchanged and the range in which you can attack is still 50.0-200.0% your NW.
I'm aware earthgraphs is slow to update, I'm taking data from a few days ago, when I made the hit.
I had checked my NW, and I was at less than 2x his NW, I was at roughly 1.8x-1.9x the target NW at the time.