Rails, Ruby, memory: does Ruby release memory as it is garbage collected

rubyonrails-talk
1

I watched this video on memory leaks from the author of the derailed gem https://www.youtube.com/watch?v=m2nj5sUE3hg&t=1s

He says that once Ruby grabs memory, it never releases it back to the OS. This was in 2015. Is this this true today?