There are multiple postings of the plastic edging that inserts into the bottom of the shower door from the factory breaking off. Some have had it replaced under warranty several times with the same result.
I found a ten dollar fix at Amazon, https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1
This edging is flexible, applies with the included peel and stick tape and installs in five minutes. The roll is eight feet long so you have enough to do the door three or four times.
Cut a piece longer then you need and place it in the sun and warm it up and straighten it out before applying. You can cut it with household scissors, clean the bottom of the shower door frame with alcohol and apply to the bottom inch of the door frame so it guides the water away from the bottom gap back into the shower.
To be clear, this does not snap into the bottom of the door like OEM, it sticks to the bottom frame facing into the shower. The "L" shape deflects the water back into the shower floor rather than flowing into the bottom sill / "shower door track".
Another thing you can do is add some sealer to the sides of the bottom sill / "shower door track" to additionally direct water flow away from the outside.
I did this on my 2014 27FB Serenity five years ago and the same piece is still on there and it does not leak any water outside the shower door at all.