Why? You then go on with some sounds advice about letting them finish, not sure why you are telling him to starve his nice plants. I had a Dinafem Critical Jack photo go for 16 weeks in flower. OP I would just stay the course, your girls look fine.
They are autos ... they are hardwired to finish UNDER a preset life.
Sure photo strains can run 15 weeks or so. But autos can and often do finish under the normal 90 day windows. SATIVA heavy can go long from time to time. All I grow is autos.
Autos CAN operate like a photo seed , sometimes requiring a force or light manipulation down on light cycle to finish. Those look perfectly normal for time frame. A ween down in Nutes is perfectly normal for the plant to use its “ stored “ resources ( and fade ) as it is LIVING off of itself. Not only are you matching the closing end of life for the auto , you resist the constant buildup of unnecessary Nutes that the final stages will not FULLY utilize.
By letting the plant PULL from itself , helps burn off the excess Nutes. IF any.
This killing off the myth of flushing at end since you are not adding excess.