Unbidden took 20k fleet power by doing nothing

Pretty much that, i attacked on like 56k unbidden fleet with a fleet powe of 170k (aprox) but at the end of that fight i lost almost everything, so i reloaded and used the invincible code to watch wtf happened and just by moving my fleet, i lost 20k fleet power from 79k (on just one fleet) to 55k, i didnt noticed about the rest.

I reloaded again, upgraded the ships and to my surprise, instead of getting more powe i dropped again from 79k to 63k

I already gave up with that save, i just wanna know what happened? Any ideas?