The selfie incident happened during stage 15 of the Tour de France, around 130 km (80 miles) from the day's finish line.
Tour de France marred by pileups
Kuss, who was knocked off balance by the spectator, is a teammate of defending champion Jonas Vingegaard.
Other cyclists from Team Jumbo–Visma — Nathan van Hooydonck and Dylan van Baarle — were also caught up in the crash.
"Please be always aware when watching cycling at the side of the road," the team tweeted.
All of the riders involved in the accident were able to resume the race.
The incident came a day after another major pileup on Saturday that saw dozens of riders hit the ground.
Saturday's crash caused three riders to drop out in the aftermath, with four others abandoning the race later on Saturday.
In 2021, a French woman was fined €1,200 ($1,350) after she held a large sign in the way of the cyclists, causing a massive pileup that forced several riders to pull out of the race.
Last month, Swiss cyclist Gino Mäder died after he plunged into a ravine during the Tour de Suisse.
