If by overpowered you meant the exact opposite, then sure.
Classic tree form came with a movement reduction. ( I hear that’s great for pvp) It had limited spells, no decurse or remove poison. No healing touch. No cc. It locked you out of all your offensive spells. Not to mention, hots are dynamic. Meaning the healing buff granted by ToL is lost the moment you shift out. You couldn’t just snapshot beefy hots let them tic.
By the time these issues were addressed, the form was removed.
Overpowered is not a word any r-druid would use to describe classic ToL. You don’t have a clue what you’re talking about.