I had not come across the term 'gagging away' before. I read it today in The Guardian, writing about the USA mens 4 x 100m relay team.

"Even without Noah Lyles, who was out of the lineup due to Covid, the US entered the race as favorites. But over the past 20 years, they’ve had a knack for gagging away Olympic opportunities. The last time they captured a medal was in 2012, but that was later stripped for a doping violation."

A quick google revealed a few uses of the term, the earliest back in 2003. It does not appear that common.