Fey Sentinel feat not working correctly

The new Fey Sentinel feat, part of the Subscriber Content, says:

"You always have the Entangle spell prepared. Once per long rest, you can cast it without expending a spell slot. You can also cast it using spell slots you have of the appropriate level. ... At character level 5, you always have the Plant Growth spell prepared and can cast it in the same way."

The Plant Growth part of the feature doesn't work. I currently have a 20th level character who has access to second level spell slots, and no higher. Entangle shows up in their spell list, but Plant Growth doesn't. The feat doesn't say you need access spell slots of the appropriate level - just that you be 5th level or higher - so this character should be able to cast Plant Growth once per long rest without expending a spell slot.

I just noticed this as well for my level 5 Ranger. I upped the character's level to 9 to see if having a third level spell slot would fix this; it did not. I then tried making a level 5 druid to see if it would work on a full caster with third level slots would have the spell prepared on my list. I can say that this detail of the feat does not work correctly because the spell is not on my druid's prepared spell list.