I think the refund feature is not intended for testing any game and getting money back.
This is the first sentence from the Steam Refunds Policy page: https://store.steampowered.com/steam_refunds
You can request a refund for nearly any purchase on Steam—for any reason.
It's almost like something happened in 2020 to cause a big spike. I wonder what that could have been, and if it is still the case.
Ah, life is full of mysteries.