Survey in EUW League Store on monetization
Not sure about other regions but I got a pop up asking for Feedback in the store just now.
It was mostly about League's monetization methods, how satisfying they feel, time-gated content, loot from different hextech chests and orbs, if it feels gratifying to spend your time playing league in terms of rewards compared to other games - also mentioned quality of the skins and theme/champ selection.
I thought it was pretty interesting and would recommend if you get the pop-up to also fill the survey out especially now with all the discussion around f2p rewards happening. :)