This is a decades old concept. I do not think it has been used in flight since the early X-plane program days. There has been more lab and ground experiments on the concepts.
This could be another bold technology choice for SpaceX to once again raid the NASA warehouses of promising but underdeveloped technology. The X-planes did not reach orbit and did not re-enter from orbit. Elon Musk and SpaceX plan to have the Super Heavy Starship re-enter Earth and Mars at far higher speeds than have been tested before. These demands will put more stress and heat on the rocket.
Elon has tweeted that the redesigned Super Heavy Starship (aka BFR) would use a lot of metal in the design. He said it would be a radical counter-intuitive design. He mentioned that the tanks, airframe and heatshield were redesigned but the shape or counters would be roughly the same. In September when Elon was announcing the Japanese billionaire, he showed simulations showing the BFS re-entering unpowered like a human parachutists before the parachute opens. SpaceX Starship needs to come in fast, unpowered and survive for the planned thousands of re-uses with ideally no maintenance.