It seems that Healing Thicket is double ticking and healing for more than intended.
Here is a Combat Log of the other morph
Enchanted Forest:
Looks pretty normal, right? Well here is a combat log of
Healing Thicket:
You can clearly see the skill healing twice within one second.
But it appears to not be happening all the time as seen here in this log:

I also noticed that my buff timer displayed a timer for Healing Thicket while it did not display one for Enchanted Forest:


The timer appears to have a duration of 4 seconds, the same duration as the morph effect, and is refreshing throughout the duration of the base skill. Perhaps the morph effect is being constantly reapplied when inside of the AoE.
I hope this isn't intended and gets fixed soon because this skill is quite strong as is.