The yellow "bananas" are an example of a female cannabis plant growing male flowers. You want to pick them off as soon as you see them as they can pollinate buds, which can end up producing some seeds. If you have lots of other female plants you might consider tossing the affected plants just so they don't pollinate others, or you can just try to be diligent about picking the bananas/male flowers off until harvest because it doesn't seem like you really have that many.
Producing bananas is usually triggered by light/heat stress, so if it's happening to the buds closest to the grow light, you might consider moving the light a little further away. But sometimes bananas are caused by genetics and there's nothing you can do to prevent them.
Luckily, a few seeds in your buds never hurt anyone, and seedy buds are still potent.
Also, since you're so close to
harvest, there isn't much time for seeds to develop anyway!
Here's
an article I wrote about hermies/bananas, if you're interested
