Weird leaf

Pretty strange leaf here... The last 7th leaflet kinda just grew straight out like that...
Whats up with it?

This is on my c99 plant from female seeds. All 3 of my plants ive started have totally different leaf strutcures. Very unique strain.

Its called an erection.

Mutation ... It happens

The C99 stock from female seeds is a F2 of an already highly unstable genetics, one would expect quite a few oddities to show in the progeny.
Such yellowing might occure do to other reasons but finding the culprint would require a picture of the whole plant and a bit more details on the grow and medium used.

C99 is an inbred line. The most common ..other than a certain leaf formation, is twinning. Two seedlings out of one seed has also occurred in my experience from Sannies Jack regular. C99 is a strain that does not like to be feminized. The strain will go auto on you if let the plant get root bound. The weirdest thing I have seen from inbred lines is a tiny leaf growing out of the stem that goes to a regular sized leaf. Tried to get a photo of it but my camera is a pos when it comes to macro shooting.

C99 pros: fast growing if in large enough pot...can be a little slow in seedling stage.
low smell
easy clone
forgiving for over fertilizing

con: if grown outdoors it tends to get moldy if your area's temp. falls below the dew point.