Caitlyn Jenner -- one of the greatest U.S. Olympians EVER -- is furious with Gwen Berry for her anthem protest ... calling the hammer thrower's actions straight-up "disgusting."
The reality TV star broke it all down to Eric Bolling on Newsmax TV on Wednesday ... explaining she could not believe Berry turned her back on "The Star Spangled Banner" after finishing in 3rd place at last weekend's 2020 U.S. Olympic Track & Field Team Trials in Eugene, OR.
"Honestly," Jenner said, "it's disgusting."
Berry -- a very vocal athlete in the fight for social justice in America -- was so pissed when the anthem played at her podium ceremony ... she did everything she could to express her dismay with the song.
The 31-year-old turned away from the flag, held up a T-shirt that read "Activist Athlete" ... and said afterward she thought officials were setting her up just to see how she'd react.