When did Ninjago turn into a trading thing like nft?

I was back in my Ninjago phase and wanted to rewatch from the beginning as I stopped after the big purple smoke season which flooded the city and they did the tornado of creation. So I stumbled upon this sub and decided to join it. Tho every post I saw up to now is like "selling minifig" "look how expensive my Lego figure is" and similar things. it feels to me like the series got turned into a "collecting and reselling for very expensive" pattern to me.. This is the NFT situation all over...