For the first time in a while, I just happened to come across the scene in which Gale talks about his loss of power. He does seem to very clearly attribute this to what went on with Mystra and his actions to win her back, and doesn't mention the tadpole at all. In his case, at least, I'm going to stick with my theory that the tadpole hasn't impacted his power level until firmer evidence otherwise appears to force me to change my mind smile.

Conversation screenshots in spoilers below ...


[Linked Image from i.imgur.com]
[Linked Image from i.imgur.com]


This conversation for my character was before Gale had told her about the orb, he had only said he needed magic items for a "condition". So there does still seem to be a bit of room for debate about how far his power loss was due to loss of Mystra's favour and how much to his near-death from absorbing the Netherese magic, as he wasn't going to be able to be completely open about that in the conversation. Still, if we take what he says here at face value, his loss of power sounds like a punishment from Mystra for his foolish and dangerous actions to attempt to win back her favour.

"You may call it 'nonsense' if you like, but I've heard nonsense, compared with which that would be as sensible as a dictionary!"