Hi there,
I would say it's simpler than overwatering or nute deficiency. Every good thing must come to an end xD.
Since that's an autoflower I would say she's reaching the end.
At some point the plant will stop taking nitrogen as well as other nutes and the "system" will shut down.
14 weeks seems like it's about it. With autos it's all about timing. If we miss a feed or make any other stress she won't reach full form by the end of the cycle.
Check what the breeder says:
"indoors it grows into a small to medium-sized plant enjoying 18 hours of light per 24 and finishing its life-cycle in 55 - 60 days"