Talking about prefabs, I remember using Unity 2018 first and when 2019 came out they introduced Nested Prefabs. It was an exciting year for me what with paying for Unity Pro and downloading the Swords and Shovels course. Not a problem of course. (as you can see I’m still learning in 2023! I do think about the people who first used Unity 5 - and I can’t help but be jealous “they did it first”.)