Apprentally, at the end of the effect period of engineered virus, the population that you would gain during the effect period(up to 24*60=1440) will be added to the planet, up to the max of course.
I do NOT know if this is intentional or reported before.

If it is a bug and not known to dan, please fix it ASAP
If it is intented or known but can't figure out how to fix in any short interval of time, please add this information to the artifact so people are at least aware of this effect.

I just lost 250 energy or so due to this little bug or lack of description~

Yeah, it's been mentioned before but should be mentioned again, as I'm not sure it's supposed to do that.