I actually almost did the same i defeated all the jerks but i gave the big lizard the feeding potion instead and i picked the power potion at night.
And it gave me the medium ending. And i can't confirm like you, it keeps looping me back.
I feel like it might be because we defeated all three jerks but didn't scare off the Beeg Lizard. At least that's what it sounds like since the potions are different and therefore unlikely the source. And I've also gotten a ton of different medium endings, just not one where I defeated them and kept the lizard around
I ran through on a new game from tutorial to the grove (Dialogue skip made that easy, tysm) and when I talk to Jester to confirm that I'm done messing around it starts to fade to white before resetting back to before that conversation. This time I even forgot to swap out the potion (I'm realizing now).