According to this article, this was happening in 2017, but the medal was brass and was smaller:
The coaches’ medals awarded at the world track championships in London are official, coming directly from the organizers. They are a smaller version of the medals presented to the athletes, and are made of brass.
“It looks the exact same, just mini; it probably should be bigger,” said Christian Coleman, the American silver medalist in the men’s 100 meters.
Coleman, competing in his first world championships, said he was unaware of the decision to award coaches medals but happily handed it to his coach, Tim Hall, after he was presented with it after his medal ceremony last Sunday.
“He said, ‘Coach, this one is for you,’ and I was like, ‘Wait, what?’” Hall said. “It was an interesting twist, and it was very appreciated. I will cherish it for a long time. It’s his first international medal, and it’s mine as well.”