Just three years removed from winning "Idol" in 2020, the non-binary singer says they're back to showing off their pipes in subway stations ... making a living off the cash and coins folks leave in their donation box.

Just Sam is documenting the full circle moment on social media ... posting clips on Instagram showing themself covering different songs in NYC subway stations.

In a since-deleted caption, Sam says they were embarrassed to be reverting back to subway singing after winning the famous reality singing competition.

According to The Sun, Sam's deleted caption said, "Back in 2021, I was super embarrassed to be going back to the trains. I didn’t want people to know that I legit needed the money. I didn't want people to know that it wasn't optional. I was disappointed in myself for allowing myself to fall so low after winning Idol, but then I had to take it easy on me and remember that I started my journey with Idol at 20 years old."

Sam won "Idol" at the height of the pandemic, during a 2020 season that went remote midseason, and contestants performed while isolated. Sam beat out runner-up Arthur Gunn to win the show's 18th season.