So, I fought my first battle this morning in the festival zone and got a level up message.

On my level 25 arena team pet Addai, who has a "this pet is no longer earning exp" philter that was applies a while ago and has not been removed from him. Ah, so I'm sitting here sorta stunned cause I have no idea how that happened. TwT

It looks like pets were earning experience from page views regardless of the philter or not.

And then, once at 100%+, a battle will tick pets over and level them up.

I have removed the ability of philtered pets to earn experience from page views and also reset your pet back to Level 25. You should re-equip one of his items when you get a chance to 'reset' his stats back to what they should be set to.