i had one cola get a bit taller and started to get bleached. I put one of those mesh bags for supermarket produce or to put around outdoor plants during a frost etc... it attenuated the light for that 1 cola and still allowed proper airflow to it. I did remove it before lights out, but probably didn't have to because it did allow airflow, but still reduced airflow, so it was just to be safe.
Anyway, something like this allos you to protect an oddball cola that's too tall without sacrificing light to the rest of the canopy.
If you deduce that it is light related....