Verstappen initially went to some lengths to cover up his identity, driving under the pseudonym of Franz Hermann, but later confirmed his appearance at the circuit.
Schumacher questions Verstappen decision
But former Williams driver and respected pundit Ralf Schumacher believes Verstappen's Red Bull chiefs wouldn't have been best pleased to see their star man out on a track renowned for its speed.
Speaking on the Sky Sports Germany podcast, Backstage Pit Lane, the German said: "If I were his team boss, I would have asked him if he was out of his mind.
"I don't think it's a good idea to do this on the Nordschleife. I know a lot of people don't like me for it, but I just find the Nordschleife incredibly dangerous.
"The DTM [Deutsche Tourenwagen Masters] was banned there in the past because it was simply too fast, and now the GT3 cars are incredibly fast.
"Things can happen so quickly. Racing in a GT3 car, okay, I can understand that, but why did it have to be the Nordschleife?"
Verstappen - who runs his own GT3 team, Verstappen.com Racing - will now turn his focus back to F1 matters as he looks to keep pace in the championship battle.
He heads into this weekend's Emilia-Romagna GP third in the drivers' standings behind the McLaren duo of Oscar Piastri and last year's runner-up, Lando Norris.