Its a random occurrence. Pure and simple. The Devs did NOT code her to behave any different than any other scimitar. They can change the name and the amount of hp/dmg but specific behavior is complicated and something they dont have the resources to change.

Why then do people believe the 5k rule works? Well its random for 1, for 2 most the people that 'think' it works do NOT have their char/ships specced properly. How do I know this?

They have rainbow boats, which means they dont capitalize on their damage potential. Which means, Donatra doesnt need to cloak because well they suck... and their ships die.

Learn to put your ships together, learn how to fight and in the name of Zeus, Ares or any other person/deity get rid of your stupid rainbow weapons. Stick with 1 energy type cannon/beam or both is fine as long as its the same.